Monitoring and Analyzing Java Applications

Command Function

Diagnoses Java applications in monitoring and analysis modes.

Syntax

Monitoring mode

Monitoring events that occur in Java processes in real time:

devkit diag jvm-jitter [-h | --help] {-a monitor | --action monitor} {-e EVENT | --event EVENT} [-c | --config] {-p PID | --pid PID}

Analysis mode

Analyzing the process information based on the collected JDK Flight Recorder (JFR) file:

devkit diag jvm-jitter [-h | --help] {-a report | --action report} {-e EVENT | --event EVENT} {-f INPUT_FILE | --file INPUT_FILE} [-o OUTPUT_PATH | --output OUTPUT_PATH]

Parameter Description

**Table 1** Common parameters
Parameter	Option	Description
-h/--help	-	Obtains help information. This parameter is optional.
-a/--action	monitor/report	Working mode of the JVM Jitter Detector. This parameter is mandatory. monitor: monitoring mode. report: analysis mode. NOTE: When jit.deoptimization is enabled for de-optimization detection, the devkit_odin.properties file is generated in the working directory (specified by the .cfg file). You need to change the value of MONITOR_JIT in the file to true (to enable monitoring).
-e/--event	jit.deoptimization/codecache.full/all	Name of the event to be monitored or analyzed. The event can be a JIT de-optimization event or a code cache statistical event. This parameter is mandatory. If different events are specified in the command line and configuration file, the event specified in the command line prevails. jit.deoptimization: JIT de-optimization event. codecache.full: code cache statistics event. all: Both JIT de-optimization and code cache statistics events are monitored.

**Table 2** Monitoring mode parameters
Parameter	Option	Description
-p/--pid	PID	ID of the Java process to be monitored. This parameter is mandatory.
-c/--config	kunpeng_devkit.cfg	Configuration file. The tool provides a template configuration file in the config/kunpeng_devkit.cfg directory. This parameter is optional.

**Table 3** Analysis mode parameters
Parameter	Option	Description
-f/--file	-	JFR file to be analyzed. This parameter is mandatory.
-o/--output	-	Path to the generated flame graphs for JFR de-optimization events. The default path is /diag/data in the tool directory. This parameter is optional.

Parameter File Description

If the tool directory is /home/DevKit-CLI-xx.xx.xx-Linux-Kunpeng, the reference path to the configuration file is /home/DevKit-CLI-xx.xx.xx-Linux-Kunpeng/diag/config/kunpeng_devkit.cfg.

The verification file can be used to check whether the .cfg file content is correct. The verification file path is /home/DevKit-CLI-xx.xx.xx-Linux-Kunpeng/diag/config/kunpeng_devkit.xsd.

**Table 4** Parameters in the **kunpeng_devkit.cfg** file
Parameter	Description
<jvm.DeoptimizationStatistics>
<enabled>	Indicates whether to enable event collection. The default value is false. To enable event collection, change the value to true.
<period>	Sampling interval, which defaults to 1 second. Separate the number and unit using a space. The unit can be second, minute, hour, or day (ms/s/m/h/d).
<duration>	Sampling duration, which defaults to 0 seconds (indicating non-stop sampling). Separate the number and unit using a space. The unit can be second, minute, hour, or day (ms/s/m/h/d).
<jitTraceThreshold>	Threshold for triggering fine-grained JIT event collection, which defaults to 60 (calculated by computeMode) and must be greater than 0.
<jitCollectDuration>	Sampling duration for each fine-grained JIT event collection, which defaults to 10 seconds.
<computeMode>	Method for calculating the collection threshold, which defaults to deoptimizationCount. The options are as follows: deoptimizationCount: counts only the number of incremental de-optimizations. compileCount: counts the number of incremental de-optimizations and the number of compilations. addCount: calculates the number of incremental de-optimizations and the number of incremental compilations.
<jfrDirPath>	Path to the JFR file generated by the collection event. The devkit_odin_jfr folder is generated in the custom directory. If you do not have the directory permission, the current working directory or /tmp directory is used.
<totalJfrFileSize>	Maximum total size of all JFR files in the devkit_odin_jfr folder, in MB, which defaults to 200 MB. The value 0 indicates that the size is not limited.
<singleJfrFileSize>	Maximum size of each single JFR file, in MB, which defaults to 12 MB. The value 0 indicates that the size is not limited.
<CompilerInlining>	Adds method inlining event collection. The default value is false.
<Compilation>	Adds compilation event collection. The default value is false.
<CompilationFailure>	Adds compilation failure event collection. The default value is false.
<CompilerConfiguration>	Adds compilation configuration event collection. The default value is false.
<CompilerPhase>	Adds compilation phase event collection. The default value is false.
<JITRestart>	Adds restart event collection. The default value is false.
<jvm.CodeCacheStatistics>
<enabled>	Indicates whether to enable event collection. The default value is false. To enable event collection, change the value to true.
<period>	Sampling interval, which defaults to 1 second. Separate the number and unit using a space. The unit can be second, minute, hour, or day (ms/s/m/h/d).
<duration>	Sampling duration, which defaults to 0 seconds (indicating non-stop sampling). Separate the number and unit using a space. The unit can be second, minute, hour, or day (ms/s/m/h/d).
<codeCacheTraceThreshold>	Threshold for triggering fine-grained code cache event collection. The default value is 0.35 (percentage of code cache events to all events). The value ranges from 0 to 1.
<codeCacheAlarmThreshold>	Threshold for triggering code cache event alarms. The default value is 0.75 (percentage of code cache events to all events). The value ranges from 0 to 1.

Parent topic: JVM Jitter Detector