7.6.10 -XX:[+|-]HitachiVerboseGCPrintThreadCount

-XX:[+|-]HitachiVerboseGCPrintThreadCount specifies whether the number of Java threads is to be output to the Java VM log file.

Description

-XX:[+|-]HitachiVerboseGCPrintThreadCount specifies whether the number of Java threads is to be output to the Java VM log file. This information can be used to monitor the number of Java threads.

The memory to be used for a stack is used by individual threads as the C heap. As the number of threads increases, the amount of memory used as the C heap also increases. By specifying the -XX:+HitachiVerboseGCPrintThreadCount option, you can monitor the number of Java threads and determine the amount of memory being used as the C heap.

If the number of threads reaches the maximum number set by the OS, you might not be able to create additional threads.

Prerequisite option

-XX:+HitachiVerboseGC

Format of output

[id] <date> (Skip Full:full_count, Copy:copy_count) 
[gc_kind gc_info, gc_time secs][Eden: eden_info][Survivor: survivor_info]
[Tenured: tenured_info][Metaspace: Metaspace_info]
[class space: class_space_info] [cause:cause_info] [User: user_cpu secs]
[Sys: system_cpu secs][IM: jvm_alloc_size, mmap_total_size, malloc_total_size]
[TC: thread_count]

The following provides details about the output item and content when this option is specified.

Output item	Output content
`thread_count`	Number of Java threads

Syntax

-XX:[+|-]HitachiVerboseGCPrintThreadCount

Specifiable values

Type: String

-XX:+HitachiVerboseGCPrintThreadCount: Outputs the number of Java threads.
-XX:-HitachiVerboseGCPrintThreadCount: Does not output the number of Java threads.

Default value

If the definition item is omitted:: -XX:+HitachiVerboseGCPrintThreadCount

Examples

Example 1 (if SerialGC is selected when the -XX:+HitachiVerboseGC option is selected)

[VGC]<Thu Oct 02 10:38:53.658 2014>(Skip Full:1,Copy:0)
[Full GC 770K->682K(8064K), 0.0050003 secs][DefNew::Eden: 88K->0K(2304K)]
[DefNew::Survivor: 0K->0K(256K)][Tenured: 681K->682K(5504K)] 
[Metaspace: 3634K(4492K, 4492K)->3634K(4492K, 4492K)]
[class space: 356K(388K, 388K)->356K(388K, 388K)] 
[cause:System.gc][User: 0.0000000 secs][Sys: 0.0000000 secs]
[IM: 11944K, 12448K, 0K][TC: 22][DOE: 0K, 0][CCI: 1173K, 245760K, 2496K]

Example 2 (if G1GC is selected when the -XX:+HitachiVerboseGC option is selected)

GC-related log

[VG1]<Thu Oct 02 10:38:56.193 2014>
[Full GC 753K/2048K(8192K)->678K/1024K(8192K), 0.0097901 secs][Status:-]
[G1GC::Eden: 1024K(2048K)->0K(2048K)][G1GC::Survivor: 0K->0K]
[G1GC::Tenured: 1024K->1024K][G1GC::Humongous: 0K->0K]
[G1GC::Free: 6144K->7168K] [Metaspace: 3634K(4492K, 4492K)->3634K(4492K, 4492K)]
[class space: 356K(388K, 388K)->356K(388K, 388K)] [cause:System.gc]
[RegionSize: 1024K][Target: 0.2000000 secs][Predicted: 0.0000000 secs]
[TargetTenured: 0K][Reclaimable: 0K(0.00%)][User: 0.0000000 secs]
[Sys: 0.0000000 secs][IM: 20459K, 21920K, 0K][TC: 35][DOE: 0K, 0]
[CCI: 1172K, 245760K, 2496K]

Concurrent Marking related log

[VCM]<Wed Jul 24 11:45:20 2013>[Concurrent Root Region Scan Start]
[User: 0.0000000 secs][Sys: 0.0000000 secs]
[VCM]<Wed Jul 24 11:45:20 2013>[Concurrent Root Region Scan End]
[User: 0.0126134 secs][Sys: 0.0146961 secs]
[VCM]<Wed Jul 24 11:45:20 2013>[Concurrent Mark Start][User: 0.0000000 secs]
[Sys: 0.0000000 secs]
[VCM]<Wed Jul 24 11:45:34 2013>[Concurrent Mark End][User: 0.0156250 secs]
[Sys: 0.2495800 secs]

Example 3 (if SerialGC is selected when the -XX:+HitachiCommaVerboseGC option is selected)

VGC,Thu Oct 02 10:38:52.442 2014,1,0,0,Full GC,770,682,8064,0.0040002,88,0,2304,
0,0,256,681,682,5504,3634,3634,4492,3634,3634,4492,356,356,388,356,356,388,1,0.
0000000,0.0000000,11913,12448,0,22,0,0,1173,245760,2496

Example 4 (if G1GC is selected when the -XX:+HitachiCommaVerboseGC option is selected)

GC-related log

VG1,Thu Oct 02 10:38:54.920 2014,Full GC,753,2048,8192,678,1024,8192,0.0064767,
-,1024,2048,0,2048,0,0,1024,1024,0,0,6144,7168,3634,3634,4492,3634,3634,4492,
356,356,388,356,356,388,1,1024,0.2000000,0.0000000,0,0,0.00,0.0000000,
0.0000000,20459,21920,0,35,0,0,1171,245760,2496

Concurrent Marking related log

VCM,Fri Jul 26 21:35:50 2013,Concurrent Mark Start,0.0000000,0.0000000
VCM,Fri Jul 26 21:35:50 2013,Concurrent Mark End,0.0124532,0.0245698

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