-XX:[+|-]HitachiVerboseGCPrintThreadCount (Option to output the number of threads)

Format

-XX:+HitachiVerboseGCPrintThreadCount
This option outputs the number of Java threads.
-XX:-HitachiVerboseGCPrintThreadCount
This option does not output the number of Java threads.

Description

Specifies whether to output the number of Java threads to the JavaVM log file in order to monitor the number of Java threads.

A thread individually allocates the memory to be used for a stack as C heap. Therefore, if the number of threads increase, the allocated C heap amount also increases in proportion to the number of threads. By specifying the -XX:+HitachiVerboseGCPrintThreadCount option, you can monitor the number of Java threads as well as understand the amount of C heap that is allocated.

Default value
  • -XX:+HitachiVerboseGCPrintThreadCount
Prerequisite options
  • -XX:+HitachiVerboseGC

Output format

[id] <date> (Skip Full:full_count, Copy:copy_count, Inc:inc_count) [gc_kind gc_info, gc_time secs][Eden: eden_info][Survivor: survivor_info][Tenured: tenured_info][Perm: perm_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][DOE: doe_alloc_size, called_count]

The output contents are explained below. Note that the following explains the items output by this option. For items other than explained below, see the output format described in -XX:[+|-]HitachiVerboseGC (Option for extended verbosegc information output).

thread_count
Specifies the number of Java threads.

Examples of output

[VGC]<Wed Jan 27 13:03:36 2010>(Skip Full:0,Copy:0)[GC 489K->152K(3520K), 0.0156080​ secs][DefNew::Eden: 489K->0K(2048K)][DefNew::Survivor: 0K->63K(64K)][Tenured: 0K->88K(1408K)][Perm: 1867K->1867K(8192K)][cause:ObjAllocFail][IM: 729K, 928K, 0K][TC: 509]