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Monitoring and ManagementLocate this document in the navigation structure

Use

There are different tools you can use for monitoring and administration purposes. See section Tools for an overview.

Procedure

Monitoring the GC

Recommendation

For a detailed analysis turn on the GC statistic trace level 6 using jvmmon. You can also dump the GC history with this tool, if, for example, an interesting GC has just occurred.

For more information on GC history options, see Configuration and Setup of SAP JVM – Configuring GC History

SAP JVM GC Statistic

A garbage collection statistic is automatically printed by the SAP JVM whenever a GC has taken more than 60 seconds. This GC statistic contains a main section, which describes the long running GC, followed by several sections for each GC event. Within the SAP NetWeaver AS Java, you will find this trace output in dev_server0 and std_server0.out in the work directory (/usr/sap/<SID>/<inst_no>/work).

Does my Server Have a GC Issue?

If application performance is not satisfactory and a garbage collection issue is suspected, look for GC statistic records in the trace files.

  • Frequent Full GCs:

    The GC cannot free enough memory in the old generation. It is triggered frequently. Solutions: increase the old generation, fix a memory leak, reduce the load of the server or increase the number server nodes.

  • Long Running GCs:

    If the GC duration is much more than the CPU time consumption, either the server (the hardware box) is under high load and no more CPU resources are available or the OS needs to page in parts of the heap (search the dev_server<N> or std_server<N> trace files for "suspicious long running GC").