Confluence の Fix java.lang.OutOfMemoryError

要約

When Confluence Data Center stops working and java.lang.OutOfMemoryError is appearing in the logs, adding memory to the JVM heap will get things running again.

ソリューション

Error type and memory size

Java applications like Jira, Crowd, and Confluence run in a "Java virtual machine" (JVM). When started, the JVM is allocated a certain amount of memory, which it makes available to applications like Confluence. By default, JVMs are allocated 64Mb of memory, no matter how many gigabytes of memory your server may actually have available. 64Mb is inadequate for most Confluence installations, so this needs to be increased.

Determine the type of error message

Look in the atlassian-confluence.log to see which type of out-of-memory (OOM) error you're receiving. There are three common messages:

1. ヒープ領域

2. PermGen Space

3. Garbage Collection (GC) Overhead

利用可能なシステム メモリの決定

Windows の場合

From the Task Manager Dialog (Press ctrl-alt-delete), select the Performance tab.

Linux の場合

Run this from the shell prompt to view memory usage.

ガイダンス

The default values supplied with Confluence are sufficient for small installations. Please refer to Managing Application Server Memory Settings and Server Hardware Requirements Guide for more details.

We aren't able to give a concrete recommendation for the amount of memory to allocate because that will depend greatly on your server setup, the size of your user base, and their behavior. Adjust and monitor memory settings based on system behavior. Regularly check logs for -Xms and -Xmx adjustments and watch for persistent GC delays or OOM errors. If issues continue despite adjustments, generate and analyze heap dumps or contact support.

For reference, the 3 most common parameters used to change the memory (heap) allocation are:

• Xms - the minimum size of the heap

• Xmx - the maximum size of the heap

• XX:MaxPermSize - the maximum size of PermGen (this is not used in Java 8 and above)

  Need advice regarding how much memory you should use? Here are some examples of hardware specifications.

If you decide to increase the memory settings, there are a few general guidelines to follow:

Increase Xmx in small increments (1-2GB at a time), until you no longer experience the OOM error

Increasing the heap beyond the capabilities of your server to adequately Garbage Collect can cause performance problems or freezing.

If your error is java.lang.OutOfMemoryError: PermGen space

Increase the XX:MaxPermSize parameter in 256MB increments until the error stops occurring.

If your error does not reference PermGen, there is no need to increase it

PermGen is used to store classes, and is generally quite static in size. It's been removed as of Java 8.

Setting Xms and Xmx

• Consider setting Xms and Xmx to the same value, especially for environments with high memory usage or frequent Garbage Collection (GC) issues (e.g., -Xms4g -Xmx4g or higher). This can improve GC performance and system stability.

• It is possible to set the Xms and Xmx values as either gigabytes or megabytes

• When setting these values in megabytes, set the value by multiplying the desired memory level by 1024. For example, to set the memory at 2 gigabytes, configure the Xms and Xmx to 2048m (2GB x 1024MB):

• 同じ例でギガバイトを使う場合は次のようにします。

• ⚠️ When setting the value in gigabytes, do not use .5 increments as this will cause the JVM to not start properly

Add memory to the JVM

Linux

Linux での手順を展開して確認

Add memory in Linux by modifying setenv.sh

1. Confluence をシャットダウンします。

2. 編集 <confluence-install>/bin/setenv.sh

3. Find the line where the node's memory is set

   1. For Xms and Xmx, it should look similar to this

      CATALINA_OPTS="[...] -Xms<memory size> -Xmx<memory size> [...] ${CATALINA_OPTS}"

   2. For PermGen, it should look similar to this

      CATALINA_OPTS="[...] XX:MaxPermSize=<memory size> [...] ${CATALINA_OPTS}"

4. Increase the values

   1. Xmx is the maximum amount

   2. Xms is the starting amount

5. Confluence を再起動します。

Windows (starting from a .bat file, not a service)

展開して Windows .bat ファイルの手順を表示

Add memory in Windows by modifying setenv.bat

1. Confluence をシャットダウンします。

2. 編集 <confluence-install>\bin\setenv.bat

3. Find the line where the node's memory is set

   1. For Xms and Xmx, it should look similar to this

      CATALINA_OPTS="[...] -Xms<memory size> -Xmx<memory size> [...] ${CATALINA_OPTS}"

   2. For PermGen, it should look similar to this

      CATALINA_OPTS="[...] XX:MaxPermSize=<memory size> [...] ${CATALINA_OPTS}"

4. Increase the values

   1. Xmx is the maximum amount

   2. Xms is the starting amount

5. Confluence を起動します。

Windows サービス

Follow the instructions in How to set system properties for Confluence running as a service on Windows

Verify your settings

To verify what settings are in place after restarting, check atlassian-confluence.log for the last startup and search for "-Xms" or "-Xmx".

Alternatively, on Linux, run this to see the environment parameters.