Error: Too many open files | AEM

The article addresses the issue where the log files contain the error 'Too many files’ as a result of which Adobe Experience Manager (AEM) doesn’t respond.

Description description

Environment

Adobe Experience Manager

Issue/Symptoms

The log files contain the error 'Too many files’  and Adobe Experience Manager (AEM) doesn’t respond.

Resolution resolution

The solution to this problem is:

A. Find which files or sockets are left open

Note - Open file limits apply to total combined open files, pipes and sockets, not just files.

On Linux platform, the List of Open File (lsof) command can be used to debug which resources are held open by the process.

Here is a sample script to collect useful lsof output:

#!/bin/bash
if [  $# -eq 0 ]
  then
    echo "No PID specified"
    echo "Run command with PID, for example:"
    echo "lsof-script.sh 12345"
    exit 2
fi

JAVA_PROCESS_PID=$1

lsof -p $JAVA_PROCESS_PID > lsof-output-$JAVA_PROCESS_PID.txt

echo "Files open by the process:"
cat lsof-output-$JAVA_PROCESS_PID.txt |  wc -l

echo "Generated output file with counts of grouped open files lsof-sorted-counts-$JAVA_PROCESS_PID.txt"
cat lsof-output-$JAVA_PROCESS_PID.txt | awk '{print $9}' | sed -e "s/\(.*\)\(segmentstore\).*$/\1\2/" |  sed -e "s/\(.*\)\(repository[ /] index\).*$/\1\2/" | sed -e "s/\(.*\)\(felix[ /] bundle\).*$/\1\2/" |  sed -e "s/\(.*\)\([ /] lib\).*$/\1\2/" |  sed -e "s/\(.*\)\([ /] logs\).*$/\1\2/" |  sed -e "s/\(.*\)\([ /] ext\).*$/\1\2/" | sort | uniq -c | sort -rn -k1 > lsof-sorted-counts-$JAVA_PROCESS_PID.txt

echo "Total open files in OS:"
lsof | wc -l

Sample output:

$> ./lsof-script.sh 18070
Files open by the process:
    1995
Generated output file with counts of grouped open files: lsof-sorted-counts-18070.txt
Total open files in OS:
   18399

Inspect the output of the generated lsof-sorted-counts-*.txt file.  It shows which files or sockets are currently held open by the process.

If you find open sockets or files listed that shouldn’t still be open, then it is likely due to an application bug. Update your application code to close files and sockets after using them.

A common cause of lingering open sockets is custom code that makes web service. In many cases, libraries like Apache Commons HttpClient are used but connections are never closed by the developers. See this article for details on Apache Commons HttpClient.

B. Increase the limit for the shell session

Check the user’s limit for maximum open files, and then run the following as the same user that AEM process runs as:

ulimit -Sn ulimit -Hn

When using the default start script of AEM/CQ, do the following to increase the limit:

If you see the error -bash: ulimit: open files: cannot modify limit: Operation not permitted when starting AEM, then the configuration above doesn’t work.

Instead, it’s necessary to increase the limit in /etc/security/limits.conf. See below for details on how to reconfigure the user limit.

If you are using a third-party application server such as JBoss or Websphere, follow the sections below and verify with the vendor’s documentation.

Note: If none of the configurations in this article solve the problem, then see what files are open using the command lsof -p (-p is the process id of the problematic process). It could be that your application is leaving file handles open. If you see that the handles are being held mostly by AEM and not your application, then contact support.

C. Increase the user’s limits

To change the maximum number of open files for non-root users, change the file/etc/security/limits.conf. You can set the limit on a per-user basis:

crx_process_username soft nofile 8092

crx_process_username hard nofile 20000

Note: This configuration doesn’t take effect until the next time the user logs in.

D. Increase the system limit

Sometimes, the user limit is high enough, but the system itself has hit its maximum number of files. Run the following as su/root user:

Note: This configuration doesn’t take effect until the next time the user logs in.

Cause

The cause is one of two possibilities:

Additional information

This error occurs when the system or user is using its maximum number file handles.

You can also do the following: