Monitoring and Maintaining Your AEM instance

After your AEM instances have been deployed certain tasks will be needed to monitor and maintain their operation, performance and integrity.

A key factor here is that to recognize potential issues you need to know how your systems looks and behaves under normal conditions. This is best done by monitoring the system and collecting information over a period of time.

Check	Considerations	Comment / Actions
Backup plan.		See how to Backup your Instance.
Disaster recovery plan.	Your company’s disaster recovery guidelines.
An error tracking system is available for reporting problems.	For example, bugzilla, jira, or one of many others.
File systems are being monitored.	The CRX repository will “freeze” if there is insufficient free disk space. It will resume once space becomes available.	" *ERROR* LowDiskSpaceBlocker" messages can be seen in the log file when free space becomes low.
Log files are being monitored.
System monitoring is (constantly) running in the background.	Including CPU, memory, disk and network usage. Using for example, iostat / vmstat / perfmon.	Logged data is visualized and can be used for tracking performance problems. Raw data is also accessible.
AEM performance is being monitored.	Including Request Counters to monitor traffic levels.	If a significant, or long term loss, of performance is seen, detailed investigation should be made.
You are monitoring your Replication Agents.
Regularly purge workflow instances.	Repository size and workflow performance.	See Regular Purging of Workflow Instances.

Backups

It is good practice to take backups of:

• Your software installation - before/after significant changes in the configuration
• The content held within the repository - regularly

Your company will probably have a backup policy that you will need to follow, additional considerations of what to backup and when include:

• how critical the system and data is.
• how often changes are made to either the software or data.
• volume of data; capacity can occasionally be an issue, as can the time needed to perform the backup.
• whether your backup can be made while users are online; and if possible, what is the performance impact.
• the geographical distribution of users; i.e. when is the best time to backup (to minimize impact)?
• your disaster recovery policy; are there guidelines on where the backup data has to be stored (e.g. offsite, specific medium, etc).

Often a full backup is taken at regular intervals (e.g. daily, weekly or monthly), with incremental backups in between (e.g hourly, daily or weekly).

Backing up your software installation

After installation, or significant changes in the configuration, take a backup of your software installation.

To do this, you need to back up your entire repository and then:

1. Stop AEM.
2. Back up the entire <cq-installation-dir> from your file system.

Backing up your repository

The Backup and Restore section of the CRX documentation covers all issues related to backups of the CRX repository.

For full details of making an online “hot” backup see Creating an Online Backup.

Version Purging

The Purge Versions tool is intended for purging the versions of a node or a hierarchy of nodes in your repository. Its primary purpose is to help you reduce the size of your repository by removing old versions of your nodes.

This section deals with maintenance operations related to the versioning feature of AEM. The Purge Version tool is intended for purging the versions of a node or a hierarchy of nodes in your repository. Its primary purpose is to help you reduce the size of your repository by removing old versions of your nodes.

Overview

The Purge Versions tool is available in the Tools console under Versioning or directly at:

https://<server>:<port>/etc/versioning/purge.html

Start Path An absolute path on which the purge must be done. You can select the Start Path by clicking the repository tree navigator.

Recursive When purging data you can choose between performing the operation on one node or on a whole hierarchy by selecting Recursive. In the last case the given path defines the root node of the hierarchy.

Maximum versions to keep The maximum number of versions to be kept for a node. When these number exceeds this value, the oldest versions are purged.

Maximum version age The maximum age of the version of a node. When the age of a version exceeds this value, it is purged.

Dry Run Because removing versions of your content is definite and can not be reverted without restoring a backup, the Purge Versions tool provides a dry run mode that allows you to preview the purged versions. To launch a dry run of the purge process, click Dry Run.

Purge Launch the purge of the versions on the node defined by the Start Path.

Purging Versions of a Web Site

To purge versions of a web site, proceed as follows:

1. Navigate to the Tools console, select Versioning and double-click Purge Versions.

2. Set the start path of the content to be purged (e.g. /content/geometrixx-outdoors).

   • If you want to only purge the node defined by your path, unselect Recursive.
   • If you want to purge the node defined by your path and its descendants select Recursive.

3. Set the maximum number of versions (for each node) that you want to keep. Leave empty to not use this setting.

4. Set the maximun version age in days (for each node) that you want to keep. Leave empty to not use this setting.

5. Click Dry Run to preview what the purge process would do.

6. Click Purge to launch the process.

Analyzing the Console

The Dry Run and Purge processes list all the nodes that have been processed. During the process, a node can have one of the following status:

• ignore (not versionnable): the node does not support versioning and is ignored during the process.
• ignore (no version): the node does not have any version and is ignored during the process.
• retained: the node is not purged.
• purged: the node is purged.

Moreover the console provides useful information about the versions:

• V 1.0: the version number.
• V 1.0.1*: the star indicates that the version is the current one.
• Thu Mar 15 2012 08:37:32 GMT+0100: the date of the version.

In the next example:

• The Shirts versions are purged because their version age is greater than 2 days.
• The Tonga Fashions! versions are purged because their number of versions is greater than 5.

Working with Audit Records and Log Files

Auditing records and log files relating to Adobe Experience Manager (AEM) can be found at various locations. The following is provided to give you an overview of what you can find where.

Working with Logs

AEM WCM records detailed logs. After you unpack and start Quickstart, you can find logs in:

• <cq-installation-dir>/crx-quickstart/logs/
• <cq-installation-dir>/crx-quickstart/repository/

Log file rotation

Log file rotation refers to the process that limits the growth of file by creating new file periodically. In AEM, a log file called error.log will be rotated once a day according to the given rules:

• The error.log file is renamed according to the pattern {original_filename} .yyyy-MM-dd. For example on July 2010 11th, the current log file is renamed error.log-2010-07-10, then a new error.og is created.
• Previous log files are not deleted, so it is your responsibility to clean old log files periodically to limit the disk usage.

Finding the Log Files

Various log files are held on the file server where you installed AEM:

• <cq-installation-dir>/crx-quickstart/logs

  • access.log

    All access requests to AEM WCM and the repository are registered here.

  • audit.log

    Moderation actions are registered here.

  • error.log

    Error messages (of varying levels of severity) are registered here.

  • ImageServer-<PortId>-yyyy>-<mm>-<dd>.log

    This log is only used if dynamic media is enabled. It provides statistics and analytical information used for analyzing behavior of the internal ImageServer process.

  • request.log

    Each access request is registered here together with the response.

  • s7access-<yyyy>-<mm>-<dd>.log

    This log is only used if dynamic media is enabled. The s7access log records each request made to Dynamic Media through /is/image and /is/content.

  • stderr.log

    Holds error messages, again of varying levels of severity, generated during startup. By default the log level is set to Warning ( WARN)

  • stdout.log

    Holds logging messages indicating events during startup.

  • upgrade.log

    Provides a log of all upgrade operations that runs from the com.day.compat.codeupgrade and com.adobe.cq.upgradesexecutor packages.

• <cq-installation-dir>/crx-quickstart/repository

  • revision.log

    Revision journaling information.

Activating the DEBUG Log Level

The default log level Apache Sling Logging Configuration is Information, so debug messages are not logged.

To activate the debug log level for a Logger, set the property org.apache.sling.commons.log.level to debug in the repository. For example, on /libs/sling/config/org.apache.sling.commons.log.LogManager to configure the global Apache Sling Logging.

A line in the debug file usually starts with DEBUG, then provides the log level, the installer action and the log message. For example:

DEBUG 3 WebApp Panel: WebApp successfully deployed

The log levels are as follows:

0	Fatal error	The action has failed, and the installer cannot proceed.
1	Error	The action has failed. The installation proceeds, but a part of AEM WCM was not installed correctly and will not work.
2	Warning	The action has succeeded but encountered problems. AEM WCM may or may not work correctly.
3	Information	The action has succeeded.

Create a Custom Log File

In certain circumstances you may want to create a custom log file with a different log level. You can do this in the repository by:

1. If not already existing, create a new configuration folder ( sling:Folder) for your project /apps/<project-name>/config.

2. Under /apps/<project-name>/config, create a node for the new Apache Sling Logging Logger Configuration:

   • Name:

   org.apache.sling.commons.log.LogManager.factory.config-<identifier> (as this is a Logger)

   Where <identifier> is replaced by free text that you (must) enter to identify the instance (you cannot omit this information). For example, org.apache.sling.commons.log.LogManager.factory.config-MINE

   • Type: sling:OsgiConfig
   NOTE

   Although not a technical requirement, it is advisable to make <identifier> unique.

3. Set the following properties on this node:

   • Name: org.apache.sling.commons.log.file

     Type: String

     Value: specify the Log File; for example, logs/myLogFile.log

   • Name: org.apache.sling.commons.log.names

     Type: String[] (String + Multi)

     Value: specify the OSGi services for which the Logger is to log messages; for example, all of the following:

     • org.apache.sling
     • org.apache.felix
     • com.day

   • Name: org.apache.sling.commons.log.level

     Type: String

     Value: specify the log level required ( debug, info, warn or error); for example debug

   • Configure the other parameters as required:

     • Name: org.apache.sling.commons.log.pattern

       Type: String

       Value: specify the pattern of the log message as required; for example,

       {0,date,dd.MM.yyyy HH:mm:ss.SSS} *{4}* [{2}] {3} {5}

   NOTE

   org.apache.sling.commons.log.pattern supports up to six arguments.

   {0} The timestamp of type java.util.Date

   {1} the log marker

   {2} the name of the current thread

   {3} the name of the logger

   {4} the log level

   {5} the log message

   If the log call includes a Throwable the stacktrace is appended to the message.

   CAUTION

   org.apache.sling.commons.log.names must have a value.

   NOTE

   Log writer paths are relative to the crx-quickstart location.

   Therefore, a log file specified as:

   logs/thelog.log

   writes to:

   <cq-installation-dir>/crx-quickstart/logs/thelog.log.

   And a log file specified as:

   ../logs/thelog.log

   writes to a directory:

   <cq-installation-dir>/logs/
   (i.e. next to <cq-installation-dir>/crx-quickstart/)

4. This step is only necessary when a new Writer is required (i.e. with a configuration that is different to the default Writer).

   CAUTION

   A new Logging Writer Configuration is only required when the existing default is not suitable.
   If no explicit Writer is configured the system will automatically generate an implicit Writer based on the default.

   Under /apps/<project-name>/config, create a node for the new Apache Sling Logging Writer Configuration:

   • Name: org.apache.sling.commons.log.LogManager.factory.writer-<identifier> (as this is a Writer)

     As with the Logger, <identifier> is replaced by free text that you (must) enter to identify the instance (you cannot omit this information). For example, org.apache.sling.commons.log.LogManager.factory.writer-MINE

   • Type: sling:OsgiConfig

   NOTE

   Although not a technical requirement, it is advisable to make <identifier> unique.

   Set the following properties on this node:

   • Name: org.apache.sling.commons.log.file

     Type: String

     Value: specify the Log File so that it matches the file specified in the Logger;

     for this example, ../logs/myLogFile.log.

   • Configure the other parameters as required:

     • Name: org.apache.sling.commons.log.file.number

       Type: Long

       Value: specify the number of log files you want kept; for example, 5

     • Name: org.apache.sling.commons.log.file.size

       Type: String

       Value: specify as required to control file rotation by size/date; for example, '.'yyyy-MM-dd

   NOTE

   org.apache.sling.commons.log.file.size controls the rotation of the log file by setting either:

   • a maximum file size
   • a time/date schedule

   to indicate when a new file will be created (and the existing file renamed according to the name pattern).

   • A size limit can be specified with a number. If no size indicator is given, then this is taken as the number of bytes, or you can add one of the size indicators - KB, MB, or GB (case is ignored).
   • A time/date schedule can be specified as a java.util.SimpleDateFormat pattern. This defines the time period after which the file will be rotated; also the suffix appended to the rotated file (for identification).

   The default is '.'yyyy-MM-dd (for daily log rotation).

   So for example, at midnight of January 20th 2010 (or when the first log message after this occurs to be precise), …/logs/error.log will be renamed to …/logs/error.log.2010-01-20. Logging for the 21st of January will be output to (a new and empty) …/logs/error.log until it is rolled over at the next change of day.

   '.'yyyy-MM	Rotation at the beginning of each month
   '.'yyyy-ww	Rotation at the first day of each week (depends on the locale).
   '.'yyyy-MM-dd	Rotation at midnight each day.
   '.'yyyy-MM-dd-a	Rotation at midnight and midday of each day.
   '.'yyyy-MM-dd-HH	Rotation at the top of every hour.
   '.'yyyy-MM-dd-HH-mm	Rotation at the beginning of every minute.

   Note: When specifying a time/date:

   1. You should “escape” literal text within a pair of single quotes (’ ');

      this is to avoid certain characters being interpreted as pattern letters.

   2. Only use characters allowed for a valid file name anywhere in the option.

5. Read your new log file with your chosen tool.

   The log file created by this example will be ../crx-quickstart/logs/myLogFile.log.

The Felix Console also provides information about Sling Log Support at ../system/console/slinglog; for example http://localhost:4502/system/console/slinglog.

Finding the Audit Records

Audit records are held to provide a record of who did what and when. Different audit records are generated for both AEM WCM and OSGi events.

AEM WCM Audit records shown when Page Authoring

1. Open a page.

2. From the sidekick you can select the tab with the lock icon, then double-click on Audit Log…

3. A new window will open showing the list of audit records for the current page.

   

4. Click OK when you want to close the window.

AEM WCM Auditing records within the repository

Within the /var/audit folder, audit records are held according to the resource. You can drill down until you can see the individual records and the information they contain.

These entries hold the same information as shown when editing a page.

OSGi Audit records from the Web Console

OSGi events also generate audit records which can be seen from the Configuration Status tab -> Log Files tab in the AEM Web Console:

Monitoring Your Replication Agents

You can monitor your replication queues to detect when a queue is either down or blocked - which might in turn indicate a problem with a publishing instance or external system:

• are all required queues enabled?

• are any disabled queues still required?

• all enabled queues should have the status idle or active, which indicate normal operation; no queues should be blocked, which is often a sign of problems on the receivers side.

• if the size of the queue grows over time this can indicate a blocked queue.

To monitor a replication agent:

1. Access the Tools tab in AEM.

2. Click Replication.

3. Double-click the link to agents for the appropriate environment (either the left or the right pane); for example Agents on author.

   The resulting window shows an overview of all your replication agents for the author environment, including their target and status.

4. Click the appropriate agent name (which is a link) to show detailed information on that agent:

   

   Here you can:

   • See whether the agent is enabled.
   • See the target of any replications.
   • See whether the replication queue is currently active (enabled).
   • See whether there are any items in the queue.
   • Refresh or Clear to update the display of queue entries; this helps you see items enter and leave the queue.
   • View Log to access the log of any actions by the replication agent.
   • Test Connection to the target instance.
   • Force Retry on any queue items if required.
   CAUTION

   Do not use the “Test Connection” link for the Reverse Replication Outbox on a publish instance.

   If a replication test is performed for an Outbox queue, any items that are older than the test replication will be re-processed with every reverse replication.

   If such items already exist in a queue, they can be found with the following XPath JCR query and should be removed.

   /jcr:root/var/replication/outbox//*[@cq:repActionType='TEST']

Again you can develop a solution to detect all replication agents (located under /etc/replication/author or /etc/replication/publish), then check the status of the agent ( enabled, disabled) and the underlying queue ( active, idle, blocked).

Monitoring Performance

Performance Optimization is an interactive process which receives focus during development. After deployment it is usually reviewed after specific intervals or events.

Methods used while collecting information for optimization can also be used for ongoing monitoring.

The following lists common performance issues which occur, together with proposals on how to spot and counteract them.

Area	Symptom(s)	To increase capacity…	To reduce volume…
Client	High client CPU usage.	Install a client CPU with higher performance.	Simplify (HTML) layout.
	Low server CPU usage.	Upgrade to a faster browser.	Improve client-side cache.
	Some clients fast, some slow.
Server
Network	CPU usage low on both servers and clients.	Remove any network bottlenecks.	Improve/optimize the configuration of the client cache.
	Browsing locally on the server is (comparatively) fast.	Increase network bandwidth.	Reduce the “weight” of your web pages (e.g. less images, optimized HTML).
Web-server	CPU usage on the web-server is high.	Cluster your web-servers.	Reduce the hits per page (visit).
		Use a hardware load-balancer.
Application	Server CPU usage is high.	Cluster your AEM instances.	Search for, and eliminate, CPU and memory hogs (use code review, timing output, etc).
	High memory consumption.		Improve caching on all levels.
	Low response times.		Optimize templates and components (e.g. structure, logic).
Repository
Cache

Performance issues may stem from a number of causes that have nothing to do with your website, including temporary slowdowns in connection speed, CPU load, and many more.

It may also impact either all your visitors, or only a subset of them.

All this information needs to be obtained, sorted and analyzed before you can either optimize the general performance or solve specific issues.

• Before you experience a performance issue:

  • collect as much information as possible to build up a good working knowledge of the system under normal circumstances

• When you experience a performance issue:

  • try to replicate it with one (or preferably more) standard web-browsers, on a different client that you know has good general performance and/or on the server itself (if possible)

  • check whether anything (related to the system) has changed within an appropriate time-space, and if any of these changes could have impacted the performance

  • ask questions such as:

    • does the issue only occur at specific times?
    • does the issue only occur on specific pages?
    • are other requests impacted?

  • collect as much information as possible to compare with your knowledge of the system under normal circumstances:

Tools for Monitoring and Analyzing Performance

The following gives a short overview of some of the tools available for monitoring and analyzing performance.

Some of these will be dependent on your operating system.

Tool	Used to analyze...	Usage / More information...
request.log	Response times and concurrency.	Interpreting the request.log.
truss/strace	Page Loads	Unix/Linux commands to trace system calls and signals. Increase the log level to INFO. Analyze the number of page loads per request, which pages, etc.
Thread dumps	Observe JVM threads. Identify contentions, locks and long-runners.	Dependent on the operating system: - Unix/Linux: kill -QUIT <pid> - Windows (console mode): Ctrl-Break Analysis tools are also available, such as TDA.
Heap Dumps	Out of Memory issues that cause slow performance.	Add the: -XX:+HeapDumpOnOutOfMemoryError option to the java call to AEM. See the Troubleshooting Guide for Java SE 6 with HotSpot VM.
System calls	Identify timing issues.	Calls to System.currentTimeMillis() or com.day.util.Timing are used to generate timestamps from your code, or via HTML-comments. Note: These should be implemented so that they can be activated / deactivated as required; when a system is running smoothly the overhead of collecting statistics will not be needed.
Apache Bench	Identify memory leaks, selectively analyze response time.	basic usage is: ab -k -n <requests> -c <concurrency> <url> See Apache Bench and the ab man page for full details.
Search Analysis		Execute search queries offline, identify response time of query, test and confirm result set.
JMeter	Load and functional tests.	https://jakarta.apache.org/jmeter/
JProfiler	In-depth CPU and memory profiling.	https://www.ej-technologies.com/
JConsole	Observe JVM metrics and threads.	Usage: jconsole See jconsole and Monitoring Performance using JConsole. Note: With JDK 1.6, JConsole is extensible with plug-ins; for example, Top or TDA (Thread Dump Analyzer).
Java VisualVM	Observe JVM metrics, threads, memory and profiling.	Usage: jvisualvm or visualvm See jvisualvm, visualvm and Monitoring Performance using (J)VisualVM. Note: With JDK 1.6, VisualVM is extensible with plug-ins.
truss/strace, lsof	In depth kernel call and process analysis (Unix).	Unix/Linux commands.
Timing Statistics	See timing statistics for page rendering.	To see timing statistics for page rendering you can use Ctrl-Shift-U together with ?debugClientLibs=true set in the URL.
CPU and memory profiling tool	Used when analyzing slow requests during development.	For example, YourKit.
Information Collection	The ongoing state of your installation.	Knowing as much as possible about your installation can also help you track down what might have caused a change in performance, and whether these changes are justified. These metrics need to be collected at regular intervals so you can easily see significant changes.

Interpreting the request.log

This file registers basic information about every request made to AEM. From this valuable conclusions can be extracted.

The request.log offers a built-in way to get a look at how long requests take. For development purposes it is useful to tail -f the request.log and watch for slow response times. To analyze a bigger request.log we recommend the use of rlog.jar which allows you to sort and filter for response times.

We recommend isolating the “slow” pages from the request.log, then individually tuning them for a better performance. This is usually done by including performance metrics per component or using a performance profiling tool such as [yourkit](https://www.yourkit.com/).

Monitoring traffic on your website

The request log registers each request made, together with the response made:

09:43:41 [66] -> GET /author/y.html HTTP/1.1
09:43:41 [66] <- 200 text/html 797ms

By totaling all the GET entries within a specific periods (e.g. over various 24 hour periods) you can make statements about the average traffic on your website.

Monitoring response times with the request.log

A good starting point for performance analysis is the request log:

<cq-installation-dir>/crx-quickstart/logs/request.log

The log looks as follows (the lines are shortened for simplicity):

31/Mar/2009:11:32:57 +0200 [379] -> GET /path/x HTTP/1.1
31/Mar/2009:11:32:57 +0200 [379] <- 200 text/html 33ms
31/Mar/2009:11:33:17 +0200 [380] -> GET /path/y HTTP/1.1
31/Mar/2009:11:33:17 +0200 [380] <- 200 application/json 39ms

This log has one line per request or response:

• The date at which each request or response was made.

• The number of the request, in square brackets. This number matches for the request and the response.

• An arrow indicating whether this is a request (arrow pointing to the right) or a response (arrow to the left).

• For requests, the line contains:

  • the method (typically, GET, HEAD or POST)
  • the requested page
  • the protocol

• For responses, the line contains:

  • the status code (200 means “success”, 404 means “page not found”
  • the MIME type
  • the response time

Using small scripts, you can extract the required information from the log file and assemble the statistics you want. From these, you can see which pages or types of pages are slow, and if the overall performance is satisfactory.

Monitoring search response times with the request.log

Search requests are also registered in the log file:

31/Mar/2009:11:35:34 +0200 [338] -> GET /author/playground/en/tools/search.html?query=dilbert&size=5&dispenc=utf-8 HTTP/1.1
31/Mar/2009:11:35:34 +0200 [338] <- 200 text/html 1562ms

So, as above, you can use scripts to extract the relevant information and build up statistics.

However, once you have determined the response time, you may need to analyze why the request is taking the time it does, and what can be done to improve the response.

Monitoring the number and impact of concurrent users

Again the request.log can be used to monitor concurrency and the system’s reaction to it.

Tests must be made to determine how many concurrent users the system can handle before a negative impact is seen. Again scripts can be used to extract results from the log file:

• monitor how many requests are made within a specific time span e.g. one minute
• test the effects of a specific number of users all making the same requests at (as close as possible) the same time; e.g. 30 users clicking Save at the same time.

31/Mar/2009:11:45:29 +0200 [333] -> GET /author/libs/Personalize/content/statics.close.gif HTTP/1.1
31/Mar/2009:11:45:29 +0200 [334] -> GET /author/libs/Personalize/content/statics.detach.gif HTTP/1.1
31/Mar/2009:11:45:30 +0200 [335] -> GET /author/libs/CFC/content/imgs/logo.rZMNURccynWcTpCxyuBNiTCoiBMmw000.default.gif HTTP/1.1
31/Mar/2009:11:45:32 +0200 [335] <- 304 text/html 0ms
31/Mar/2009:11:45:33 +0200 [334] <- 200 image/gif 31ms
31/Mar/2009:11:45:38 +0200 [333] <- 200 image/gif 31ms
31/Mar/2009:11:45:42 +0200 [336] -> GET /author/libs/CFC/content/imgs/logo.rZMNURccynWcTZRXunQbbQtvuuCMbRRBuWXz0000.default.gif HTTP/1.1
31/Mar/2009:11:45:43 +0200 [337] -> GET /author/titlebar_bg.gif HTTP/1.1
31/Mar/2009:11:45:43 +0200 [336] <- 304 text/html 0ms
31/Mar/2009:11:45:44 +0200 [337] <- 304 text/html 0ms

Using rlog.jar to find requests with long duration times

AEM includes various helper tools located in:
<cq-installation-dir>/crx-quickstart/opt/helpers

One of these, rlog.jar, can be used to quickly sort request.log so that requests are displayed by duration, from longest to shortest time.

The following command shows the possible arguments:

$java -jar rlog.jar
Request Log Analyzer Version 21584 Copyright 2005 Day Management AG
Usage:
  java -jar rlog.jar [options] <filename>
Options:
  -h               Prints this usage.
  -n <maxResults>  Limits output to <maxResults> lines.
  -m <maxRequests> Limits input to <maxRequest> requests.
  -xdev            Exclude POST request to CRXDE.

For example, you can run it specifying request.log file as a parameter and show the 10 first requests that have the longest duration:

$ java -jar ../opt/helpers/rlog.jar -n 10 request.log
*Info * Parsed 464 requests.
*Info * Time for parsing: 22ms
*Info * Time for sorting: 2ms
*Info * Total Memory: 1mb
*Info * Free Memory: 1mb
*Info * Used Memory: 0mb
------------------------------------------------------
     18051ms 31/Mar/2009:11:15:34 +0200 200 GET /content/geometrixx/en/company.html text/ html
      2198ms 31/Mar/2009:11:15:20 +0200 200 GET /libs/cq/widgets.js application/x-javascript
      1981ms 31/Mar/2009:11:15:11 +0200 200 GET /libs/wcm/content/welcome.html text/html
      1973ms 31/Mar/2009:11:15:52 +0200 200 GET /content/campaigns/geometrixx.teasers..html text/html
      1883ms 31/Mar/2009:11:15:20 +0200 200 GET /libs/security/cq-security.js application/x-javascript
      1876ms 31/Mar/2009:11:15:20 +0200 200 GET /libs/tagging/widgets.js application/x-javascript
      1869ms 31/Mar/2009:11:15:20 +0200 200 GET /libs/tagging/widgets/themes/default.js application/x-javascript
      1729ms 30/Mar/2009:16:45:56 +0200 200 GET /libs/wcm/content/welcome.html text/html; charset=utf-8
      1510ms 31/Mar/2009:11:15:34 +0200 200 GET /bin/wcm/contentfinder/asset/view.json/ content/dam?_dc=1238490934657&query=&mimeType=image&_charset_=utf-8 application/json
      1462ms 30/Mar/2009:17:23:08 +0200 200 GET /libs/wcm/content/welcome.html text/html; charset=utf-8

You may need to concatenate the individual request.log files if you need to do this operation on a large data sample.

Apache Bench

To minimize the impact of special cases (such as garbage collection, etc), it is recommended to use a tool such as apachebench (see for example, ab for further documentation) to help identify memory leaks and selectively analyze response time.

Apache Bench can be used in the following way:

$ ab -c 5 -k -n 1000 "http://localhost:4503/content/geometrixx/en/company.html"
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, https://www.zeustech.net/
Licensed to The Apache Software Foundation, https://www.apache.org/

Benchmarking localhost (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests

Server Software: Day-Servlet-Engine/4.1.52
Server Hostname: localhost
Server Port: 4503

Document Path: /content/geometrixx/en/company.html
Document Length: 24127 bytes

Concurrency Level: 5
Time taken for tests: 69.766 seconds
Complete requests: 1000
Failed requests: 998
(Connect: 0, Receive: 0, Length: 998, Exceptions: 0)
Write errors: 0
Keep-Alive requests: 0
Total transferred: 24160923 bytes
HTML transferred: 24010923 bytes
Requests per second: 14.33 /sec (mean)
Time per request: 348.828 [ms] (mean)
Time per request: 69.766 [ms] (mean, across all concurrent requests)
Transfer rate: 338.20 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 3.9 0 58
Processing: 138 347 568.5 282 8106
Waiting: 137 344 568.1 281 8106
Total: 139 348 568.4 283 8106

Percentage of the requests served within a certain time (ms)
50% 283
66% 323
75% 356
80% 374
90% 439
95% 512
98% 1047
99% 1132
100% 8106 (longest request)

The numbers above are taken from a standard MAcBook Pro laptop (mid 2010) accessing the geometrixx company page, as included in a default AEM installation. The page is very simple, but not optimized for performance.

apachebench also displays the time per request as the mean, across all concurrent requests; see Time per request: 54.595 [ms] (mean, across all concurrent requests). You can change the value of the concurrency parameter -c (number of multiple requests to perform at a time) to see any effects.

Request Counters

Information about request traffic (number of requests during a specific time period) gives you an indication of the load on your instance. This information can be extracted from request.log, though using counters will automate data collection to let you see:

• significant differences in activity (ie differentiate between “many requests” and “low activity”
• when an instance is not being used
• any restarts (counters are reset to 0)

To automate information collection you can also install a RequestFilter to increment a counter on every request. Multiple counters can be used for different time periods.

The information gathered can be used to indicate:

• significant changes in activity
• a redundant instance
• any restarts (counter reset to 0)

HTML Comments

It is recommended that every project includes html comments for server performance. Many good public examples can be found; select a page, open the page source for viewing and scroll to the bottom, code such as the following can be seen:

</body>
 </html>
        <!--
        Page took 58 milliseconds to be rendered by server
         -->

Monitoring Performance using JConsole

The tool command jconsole is available with the JDK.

1. Start your AEM instance.

2. Run jconsole.

3. Select your AEM instance and Connect.

4. From within the Local application, double-click com.day.crx.quickstart.Main; the Overview will be shown as default:

   

   After this you can select other options.

Monitoring Performance using (J)VisualVM

Since JDK 1.6, the tool command jvisualvm is available. After you have installed JDK 1.6 you can:

1. Start your AEM instance.

   NOTE

   If using Java 5 you can add the -Dcom.sun.management.jmxremote argument to the java command line that starts your JVM. JMX is enabled per default with Java 6.

2. Run either:

   • jvisualvm: in the JDK 1.6 bin folder (tested version)
   • visualvm: can be downloaded from VisualVM (bleeding edge version)

3. From within the Local application, double-click com.day.crx.quickstart.Main; the Overview will be shown as default:

   

   After this you can select other options, including Monitor:

   

You can use this tool to generate thread dumps and memory head dumps. This information is often requested by the technical support team.

Information Collection

Knowing as much as possible about your installation can help you track down what might have caused a change in performance, and whether these changes are justified. These metrics need to be collected at regular intervals so you can easily see significant changes.

The following information can be useful:

• How many authors are working with the system?
• What is the average number of page activations per day?
• How many pages do you currently maintain on this system?
• If you use MSM, what is the average number of rollouts per month?
• What is the average number of Live Copies per month?
• If you use AEM Assets, how many assets do you currently maintain in Assets?
• What is the average size of the assets?
• How many templates are currently used?
• How many components are currently used?
• How many requests per hour do you have on the author system at peak time?
• How many requests per hour do you have on the publish system at peak time?

How many authors are working with the system?

To see the number of authors that have used the system since installation use the command line:

cd <cq-installation-dir>/crx-quickstart/logs
cut -d " " -f 3 access.log | sort -u | wc -l

To see the number of authors working on a given date:

grep "<date>" access.log | cut -d " " -f 3 | sort -u | wc -l

What is the average number of page activations per day?

To see the total number of page activations since server installation use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:AuditEvent)[@cq:type='Activate']

Then calculate the number of days that have elapsed since installation to calculate the average.

How many pages do you currently maintain on this system?

To see the number of pages currently on the server use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:Page)

If you use MSM, what is the average number of rollouts per month?

To determine the total number of rollouts since installation use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:AuditEvent)[@cq:type='PageRolledOut']

Calculate the number of months that have elapsed since installation to calculate the average.

What is the average number of Live Copies per month?

To determine the total number of Live Copies made since installation use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:LiveSyncConfig)

Again use the number of months that have elapsed since installation to calculate the average.

If you use AEM Assets, how many assets do you currently maintain in Assets?

To see how many DAM assets you currently maintain, use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query /jcr:root/content/dam//element(*, dam:Asset)

What is the average size of the assets?

To determine the total size of the /var/dam folder:

1. Use WebDAV to map the repository to the local file system.

2. Use the command line:

   cd /Volumes/localhost/var
   du -sh dam/
   

   To get the average size, divide the global size by the total number of assets in /var/dam (obtained above).

How many templates are currently used?

To see the number of templates currently on the server use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:Template)

How many components are currently used?

To see the number of components currently on the server use a repository query; via CRXDE - Tools - Query:

• Type XPath

• Path /

• Query //element(*, cq:Component)

How many requests per hour do you have on the author system at peak time?

To determine the requests per hour you have on the author system at peak time:

1. To determine the total number of requests since installation use the command line:

   cd <cq-installation-dir>/crx-quickstart/logs
   grep -R "\->" request.log | wc -l
   

2. To determine the start and end dates:

   vim request.log
   G / 1G: for the last/first lines
   

   Use these values to calculate the number of hours that have elapsed since installation, then the average number of requests per hour.

How many requests per hour do you have on the publish system at peak time?

Repeat the above procedure on your publish instance.

Analyzing Specific Scenarios

The following is a list of suggestions on what to check if you start experiencing certain performance problems. The list is not (unfortunately) fully comprehensive.

CPU at 100%

If the CPU of your system is constantly running at 100% then see:

• The Knowledge Base:

  • Analyze Slow and Blocked Processes

Out of Memory

Although such errors should be detected during Development and Testing, certain scenarios can slip through.

If your system is running out of memory this can be seen in various ways, including performance degradation and error messages including the subtext:

java.lang.OutOfMemoryError

In these cases check:

• the JVM settings used to start AEM

• The Knowledge Base:

  • Analyze Memory Problems

Disk I/O

If your system is either running out of diskspace, or you notice disk thrashing starting see:

• Whether you have disabled collection of debug information; this can be configured in various locations, including:

  • Apache Sling JSP Script Handler
  • Apache Sling Java Script Handler
  • Apache Sling Logging Configuration
  • CQ HTML Library Manager
  • CQ WCM Debug Filter
  • Loggers

• Whether and how you have configured Version Purging

• The Knowledge Base:

  • Too Many Open Files
  • Journal consumes too much diskspace

Regular Performance Degradation

If you see the performance of your instance deteriorating after each reboot (sometimes a week or more later), then the following can be checked:

• Out of Memory

• The Knowledge Base:

  • Unclosed Sessions

JVM Tuning

The Java Virtual Machine (JVM) has significantly improved in respect to tuning (especially since Java 7). Because of this, specifying a reasonable fixed JVM size and using the defaults will often be suitable.

If the default settings are not suitable, then it is important to establish a method to monitor and assess GC performance before attempting to tune the JVM; this can involve monitoring factors including, heap size, algorithm and other aspects.

Some common choices are:

• VerboseGC:

  -verbose:gc \
   -Xloggc:$LOGS/verbosegc.log \
   -XX:+PrintGCDetails \
   -XX:+PrintGCDateStamps
  

The resulting log can be ingested by a GC visualizer such as:

[https://www.ibm.com/developerworks/library/j-ibmtools2/](https://www.ibm.com/developerworks/library/j-ibmtools2/)

Or JConsole:

• These settings are for a “wide open” JMX connection:

  -Dcom.sun.management.jmxremote \
   -Dcom.sun.management.jmxremote.port=8889 \
   -Dcom.sun.management.jmxremote.authenticate=false \
   -Dcom.sun.management.jmxremote.ssl=false
  

• Then connect to the JVM with the JConsole; see:
  [https://docs.oracle.com/javase/6/docs/technotes/guides/management/jconsole.html](https://docs.oracle.com/javase/6/docs/technotes/guides/management/jconsole.html)

This will help you see how much memory is being used, what GC algorithms are being used, how long they take to run, and what effect this has on your application performance. Without this, tuning is just “randomly twiddling knobs”.