Memory usage and requirements

Managing Confluence's performance and memory usage really depends on what resources are available - Confluence will run faster if you give it lots of memory for its caches, but it should still be able to run quite well in low-memory environments, with the right tuning. Below are some tips on getting the most out of your Confluence site:

Confluence で利用可能なメモリ容量を増量する

See Increasing JIRA Memory for details on how to increase the memory available to web application servers typically used to run Confluence.

埋め込みデータベース

The embedded HSQL database that comes with Confluence essentially holds all your data in memory while the Confluence server is running. If you are running out of memory, you should consider migrating Confluence to some external RDBMS.

キャッシング

By default, Confluence keeps large in-memory caches of data to improve its responsiveness and the user experience. The trade off is an increase in memory requirements to support the cache. The default size of these caches will be reduced significantly in Confluence 1.5 (although this means that administrators of larger Confluence sites may need to configure the size of their caches to improve performance).

To customise confluences cache to meet your needs, see cache tuning.
To increase the amount of memory available to confluence, see allocating more memory to tomcat.

メールエラーキュー

Confluence keeps a copy of all emails that it failed to send within an internal error queue. In the event of intermittent failures such as network connectivity issues, the emails in this queue can be manually resent when the problem is fixed. Under certain circumstances, the mail queue can fill up with large objects. Since Confluence 1.4.1 the queue is regularly flushed, but if you get a lot of mail errors, you might get a spike in memory usage.

添付ファイル

大きなサイズの添付ファイルのインデックス作成では、添付ファイルをメモリに読み込む必要があります。大きなサイズの添付ファイルの場合、これは、システムリソースに一時的に負荷がかかる原因になり得ます。その結果、添付ファイルを完全にメモリに読み込むことができずにインデックス作成が失敗する場合もあります。

System backup / resort

The Confluence backup and resort process scales linearly with the size of data. This can have a significant impact on large Confluence instances where the amount of data exceeds the amount of available memory. If you are experiencing OutOfMemoryErrors during either a backup or restore, you with either need to move to per space backups or increase the memory allocated to Confluence. This is addressed in the upcoming Confluence 2.0.

If you are attempting to restore a backup and encountering the OutOfMemoryError, how much memory will you need to make it work? A good rule of thumb is to have a look at the size of the entities.xml file in your backup. This file contains all of the data Confluence will be loading, so at least that much is required. Add another 64-128Mb to ensure that Confluence has enough memory to load and function and that should be enough.

This problem has been resolved in Confluence post 1.4.x. To increase the amount of memory available to confluecne, see allocating more memory to tomcat.

Known issues that we do not have control over.

解決できないメモリの問題もいくつか存在します。たとえば、

• Oracle 10g JDBC ドライバーでのメモリリークがあります。これについてはできることはあまりありません。
• one customer found a rather nasty memory leak that appeared to originate inside Tomcat 5, but only using the IBM JDK on PowerPC.

If you're having problems that appear to be a memory leak, file an issue on http://support.atlassian.com. Our memory profiler of choice is YourKit, so if you can get a memory dump from that tool showing a leak

一部のアクションに対する応答に長時間を要している Confluence の問題

A common cause of random pauses in Confluence is the jvm running garbage collection. To determine if this is what is happening, enable verbose garbage collection and look at how long java is taking to free up memory. If the random pauses match when java is running its garbage collection, garbage collection is the cause of the pause.

Verbose garbage collection will generate log statements that indicate when java is collecting garbage, how long it takes, and how much memory has been freed.

To enable gc logging, start Confluence with the option -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -verbose:gc -Xloggc:gc.log. Replace gc.log with an absolute path to a gc.log file.

たとえば、Windows サービスでは以下を実行します。

tomcat5 //US//Confluence ++JvmOptions="-XX:+PrintGCDetails -XX:+PrintGCTimeStamps -verbose:gc -Xloggc:c:\confluence\logs\gc.log"

または、bin/setenv.sh で次のように設定します。

export CATALINA_OPTS="$CATALINA_OPTS -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -verbose:gc -Xloggc:${CATALINA_BASE}/logs/gc.log"

bin/setenv.sh を変更する場合、変更を有効にするには Confluence を再起動する必要があります。

What can you do to minimise the time taken to handle the garbage collection? See http://java.sun.com/docs/hotspot/gc1.4.2/ for details on tuning the jvm to minimize the impact that garbage collection has on the running application.