Sometimes it is necessary to collect heap dump on the FMS to analyze JVM functionality.
To manually generate an FMS (Management Server) Heap dump, run this command from the [FMS_HOME]/bin directory.
./fms --heap-dump ./dump_file_name.bin
Note: The FMS heap dump destination file path can be absolute or relative to [FMS_HOME] (e.g. C:\Quest\Foglight).
The FglAM (Agent Manager) has a very similar command to generate a Heap dump.
./fglam --heap-dump ./dump_file_name.bin
Note: The FglAM heap dump destination file path can be absolute or relative to [FGLAM_HOME]/client/[version] (e.g. C:\Quest\Foglight Agent Manager\client\6.3.0-202303162316-b841c373-7)
The FMS and FglAM can be configured to generate a Heap dump automatically if an OOM error (OutOfMemoryError) is raised, which can be useful to investigate unexplained OOM issues.
To configure the FMS to generate a Heap dump on OOM error, edit the [FMS_HOME]/config/server.config file and then restart the FMS.
# This example assumes server.vm.option2 and 3 aren't used elsewhere in this file # edit accordingly server.vm.option2 = "-XX:+HeapDumpOnOutOfMemoryError"; server.vm.option3 = "-XX:HeapDumpPath=./dump_file_name.bin";
Similarly; to configure the FglAM to generate a Heap dump on OOM error, edit the [FGLAM_HOME]/state/default/config/baseline.jvmargs.config file and then restart the FglAM.
# This example assumes vmparameter.2 and 3 are not used elsewhere in this file # edit accordingly vmparameter.2 = "-XX:+HeapDumpOnOutOfMemoryError"; vmparameter.3 = "-XX:HeapDumpPath=./dump_file_name.bin";
Note 1: When editing a config file, don't use backslash (\) for Windows paths (e.g. C:\Quest\Foglight is invalid), use forward slashes to avoid escape sequences (e.g. C:/Quest/Foglight is valid).
Note 2: Regarding the HeapDumpPath relative location, please review the notes under Generate a Heap Dump manually.
Since Foglight version 5.7.5.3, a JVM Heap Histogram can be generated from command line.
To generate an FMS Heap histogram run this command from the [FMS_HOME]/bin directory.
./fms --heap-histogram
Note: The FMS heap histogram will be written to the current FMS log file and [FMS_HOME]/state/quest-heap-histogram-dump-[date]T[time].txt (e.g. C:\Quest\Foglight\state\quest-heap-histogram-dump-2023-10-06T10-34-45.txt).
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