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 Fix Out of Memory errors by Increasing Available Memory.

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 / restore

The Confluence backup and restore 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 an OutOfMemoryError during either a backup or restore processes, then we strongly recommend that you choose and Production Backup Strategy.

If you encounter an OutOfMemoryError while restoring a backup and wish to overcome this issue by increasing memory, how much more will you need to make this process 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 issue was resolved in Confluence post 1.4.x. To increase the amount of memory available to Confluence, see Fix Out of Memory errors by Increasing Available Memory.

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 are having problems that appear to result from a memory leak, file an issue on http://support.atlassian.com. Our memory profiler of choice is YourKit. It would be helpful to us if you can provide us with a memory dump from that tool showing the 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

Confluence で偶発的に中断が生じる一般的な原因は、JVM が実行するガベージコレクションです。これが発生しているかどうかを判別するには、詳細ガベージコレクションを有効にし、Java がメモリの解放に要する時間を調べます。Java がガベージコレクションを実行しているときに偶発的な中断が生じる場合、ガベージコレクションが中断の原因です。

詳細ガベージコレクションは、Java がガベージを収集している日時、所要時間、解放されたメモリ量を示すログステートメントを生成します。

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 minimise the impact that garbage collection has on the running application.