7.6.2 -XX:[+|-]HitachiVerboseGC

Description

-XX:[+|-]HitachiVerboseGC specifies whether the extended verbosegc information is to be output when GC occurs.

Output format (for SerialGC)

[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][DOE: doe_alloc_size, called_count]
[CCI: cc_used_sizeK, cc_max_sizeK, cc_infoK]

The following provides details about the output.

Output item	Output content
id	VGC (Java VM log file identifier)
date	Start date and time of GC This information is not output if the -XX:-HitachiVerboseGCPrintDate option is specified.
full_count	Number of times output of the full GC information was skipped. This information is output if the -XX:HitachiVerboseGCIntervalTime option is specified.
copy_count	Number of times output of the CopyGC information was skipped. This information is output if the -XX:HitachiVerboseGCIntervalTime option is specified.
gc_kind	GC type. Either FullGC or GC is output.
gc_info	GC information. This information is output in the following format: area_length_before_GC -> area_length_after_GC (area_size)
gc_time	Elapsed GC time.
Eden	Eden type. DefNew::Eden is output.
eden_info	Eden information. This information is output in the following format: area_length_before_GC -> area_length_after_GC (area_size)
Survivor	Survivor type. DefNew::Survivor is output.
survivor_info	Survivor information. This information is output in the following format: area_length_before_GC -> area_length_after_GC (area_size)
Tenured	Tenured type. Tenured is output.
tenured_info	Tenured information. This information is output in the following format: area_length_before_GC -> area_length_after_GC (area_size)
Metaspace_info	Memory information of the Metaspace area. This information is output in the following format: size_of_used_Metaspace_area_before_GCK(capacity_size_of_Metaspace_area_before_GCK, commit_size_of_Metaspace_area_before_GCK)->size_of_used_Metaspace_area_after_GCK(capacity_size_of_Metaspace_area_after_GCK, commit_size_of_Metaspace_area_after_GCK)
classspace_info	Memory information of the Compressed Class Space. This information is output in the following format: size_of_used_Compressed_Class_Space_before_GCK(capacity_size_of_Compressed_Class_Space_before_GCK, commit_size_of_Compressed_Class_Space_before_GCK)->size_of_used_Compressed_Class_Space_after_GCK(capacity_size_of_Compressed_Class_Space_after_GCK, commit_size_of_Compressed_Class_Space_after_GCK) This information is not output if the functionality for the compressed object pointer is not used.
cause_info	Details on the cause of GC. This information is not output if the -XX:-HitachiVerboseGCPrintCause option is specified.
user_cpu	Amount of CPU time that the GC thread spent in user mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [User:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified.
system_cpu	Amount of CPU time that the GC thread spent in kernel mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [Sys:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified.
jvm_alloc_size	Of the total size of the areas managed in Java VM (the sum of mmap_total_size and malloc_total_size), the size of the area that is currently in use This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
mmap_total_size	Of the areas managed in Java VM, the total C heap size allocated by mmap This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
malloc_total_size	Of the areas managed in Java VM, the total C heap size allocated by malloc This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
thread_count	Number of Java threads This information is not output if the -XX:-HitachiVerboseGCPrintThreadCount option is specified.
doe_alloc_size	Cumulative size of the heap that was allocated when java.io.File.deleteOnExit() was called This information is not output if the -XX:-HitachiVerboseGCPrintDeleteOnExit option is specified.
called_count	Number of times java.io.File.deleteOnExit() was called. This information is not output if the -XX:-HitachiVerboseGCPrintDeleteOnExit option is specified.
cc_used_size	Size of the used code cache area when GC occurred. This information is output in units of kilobytes. This information is not output if the -XX:-PrintCodeCacheInfo option is specified.
cc_max_size	Maximum size of the code cache area. This information is output in units of kilobytes. This information is not output if the -XX:-PrintCodeCacheInfo option is specified.
cc_info	Maintenance information This information is not output if the -XX:-PrintCodeCacheInfo option is specified.

Format of output (for G1GC)

Log entries related to GC and log entries related to Concurrent Marking are output to the Java VM log file. The log entry for one instance of Concurrent Marking is output into two or more lines, because Concurrent Marking is executed in parallel with other applications.

Format of output for the log entries related to GC

[id]<date>[gc_kind gc_info, gc_time secs][Status:gc_status]
[G1GC::Eden: eden_info][G1GC::Survivor: survivor_info]
[G1GC::Tenured: tenured_info][G1GC::Humongous: humongous_info]
[G1GC::Free: free_info][Metaspace: Metaspace_info]
[class space: class_space_info][cause:cause_info][RegionSize: region_sizeK]
[Target: target_time secs][Predicted: predicted_time secs]
[TargetTenured: target_sizeK][Reclaimable: reclaimable_info]
[User: user_cpu secs][Sys: system_cpu secs]
[IM: jvm_alloc_sizeK, mmap_total_sizeK, malloc_total_sizeK][TC: thread_count]
[DOE: doe_alloc_sizeK, called_count][CCI: cc_used_sizeK, cc_max_sizeK, cc_infoK]

Output format of the log entries related to Concurrent Marking

[id]<date>[cm_event][User:  user_cpu secs][Sys:  sys_cpu secs]

The following provides details about the output.

Classification	Output item	Output content
Log entry related to GC	id	VG1 (Java VM log file identifier).
	date	Start data and time of GC or Concurrent Marking. This information is not output if the -XX:-HitachiVerboseGCPrintDate option is specified.
	gc_kind	Type of GC or Concurrent Marking. One of the following is output: FullGC, Mixed GC, Young GC, Young GC(initial-mark), CM Remark, or CM Cleanup.
	gc_info	Memory information of the JavaHeap area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_JavaHeap_area_before_GCK/size_of_used_JavaHeap_area_before_GC#K(size_of_JavaHeap_area_before_GC#K)->size_of_used_JavaHeap_area_after_GCK/size_of_used_JavaHeap_area_after_GC#K(size_of_JavaHeap_area_after_GC#K)
	gc_time	Amount of time for which the application stopped due to GC. This information is output in units of seconds.
	gc_status	GC status. When a To space overflow occurs, to exhausted is output. In cases other than the above, - is output. For each type of GC, the GC status is output as follows. When gc_kind is Young GC, Young GC(initial-mark), or Mixed GC: - or to exhausted is output. When gc_kind is a type other than the above: - is output.
	eden_info	Memory information of the Eden area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Eden_area_before_GC#K(maximum_size_that_can_be_acquired_by_Eden_area_before_GC#K)->size_of_used_Eden_area_after_GC#K(maximum_size_that_can_be_acquired_by_Eden_area_after_GC#K) The maximum size that can be acquired by the Eden area refers to size_of_New_area - size_of_used_Survivor_area.
	survivor_info	Memory information of the Survivor area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Survivor_area_before_GC#K->size_of_used_Survivor_area_after_GC#K
	tenured_info	Memory information of the Tenured area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Tenured_area_before_GC#K->size_of_used_Tenured_area_after_GC#K
	humongous_info	Memory information of the Humongous area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Humongous_area_before_GC#K->size_of_used_Humongous_area_after_GC#K
	free_info	Memory information of the Free area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Free_area_before_GC#K->size_of_used_Free_area_after_GC#K
	Metaspace_info	Memory information of the Metaspace area. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Metaspace_area_before_GCK(capacity_size_of_Metaspace_area_before_GCK, commit_size_of_Metaspace_area_before_GCK)->size_of_used_Metaspace_area_after_GCK(capacity_size_of_Metaspace_area_after_GCK, commit_size_of_Metaspace_area_after_GCK)
	classspace_info	Memory information of the Compressed Class Space. This information is output in the following format, where values are given in units of kilobytes: size_of_used_Compressed_Class_Space_before_GCK(capacity_size_of_Compressed_Class_Space_before_GCK, commit_size_of_Compressed_Class_Space_before_GCK)->size_of_used_Compressed_Class_Space_after_GCK(capacity_size_of_Compressed_Class_Space_after_GCK, commit_size_of_Compressed_Class_Space_after_GCK) This information is not output if the functionality for the compressed object pointer is not used.
	cause_info	Details on the cause of GC This information is not output if the -XX:-HitachiVerboseGCPrintCause option is specified.
	region_size	Size of a single region. This information is output in units of kilobytes.
	target_time	Target amount of time for which applications are stopped due to GC. This information is output in units of seconds. You can specify the target time by using the -XX:+MaxGCPauseMillis option.
	predicted_time	Amount of time for which applications will be stopped due to GC, as predicted by Java VM. This information is output in units of seconds. If the type of GC or Concurrent Marking is Full GC, CM Remark, or CM Cleanup, Java VM does not predict the stop time, and 0 is output.
	target_size	Size of the Tenured area that is subject to Mixed GC. This information is output in units of kilobytes. If the type of GC or Concurrent Marking is not Mixed GC, 0 is output.
	reclaimable_info	Information about the predicted collection size. This information is output in the following format: predicted_collection_size K(predicted_collection_rate %) The predicted collection size is output in units of kilobytes. The predicted collection rate is output as a value with two decimal places. Note that the information about the predicted collection size is output only for Young GC or Mixed GC immediately after Concurrent Marking. In other cases, Java VM does not predict the collection size, and 0 is output.
	user_cpu	Total CPU time that all GC threads spent in user mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [User:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified.
	system_cpu	Total CPU time that all GC threads spent in kernel mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [Sys:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified.
	jvm_alloc_size	Of the total size of the areas managed in Java VM (the sum of mmap_total_size and malloc_total_size), the size of the area that is currently in use This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
	mmap_total_size	Of the areas managed in Java VM, the total C heap size allocated by mmap This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
	malloc_total_size	Of the areas managed in Java VM, the total C heap size allocated by malloc This information is not output if the -XX:-HitachiVerboseGCPrintJVMInternalMemory option is specified.
	thread_count	Number of Java threads This information is not output if the -XX:-HitachiVerboseGCPrintThreadCount option is specified.
	doe_alloc_size	Cumulative size of the heap that was allocated when java.io.File.deleteOnExit() was called This information is not output if the -XX:-HitachiVerboseGCPrintDeleteOnExit option is specified.
	called_count	Number of times java.io.File.deleteOnExit() was called This information is not output if the -XX:-HitachiVerboseGCPrintDeleteOnExit option is specified.
	cc_used_size	Size of the used code cache area when GC occurred. This information is output in units of kilobytes. This information is not output if the -XX:-PrintCodeCacheInfo option is specified.
	cc_max_size	Maximum size of the code cache area. This information is output in units of kilobytes. This information is not output if the -XX:-PrintCodeCacheInfo option is specified.
	cc_info	Maintenance information This information is not output if the -XX:-PrintCodeCacheInfo option is specified.
Log entry related to Concurrent Marking	id	VCM (Java VM log file identifier).
	date	Start data and time of Concurrent Marking. This information is not output if the -XX:-HitachiVerboseGCPrintDate option is specified.
	cm_event	Status of Concurrent Marking. Concurrent Root Region Scan Start The Concurrent Root Region Scan has started. Concurrent Root Region Scan End The Concurrent Root Region Scan has ended. Concurrent Mark Start The Concurrent Mark has started. Concurrent Mark End The Concurrent Mark has ended. Concurrent Mark Stop The Concurrent Mark has stopped. Concurrent Cleanup Start The Concurrent Cleanup has started. Concurrent Cleanup End The Concurrent Cleanup has ended.
	user_cpu	Total CPU time that all GC threads spent in user mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [User:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified. If the status of Concurrent Marking is Concurrent Mark Start, 0 is output.
	sys_cpu	Total CPU time that all GC threads spent in kernel mode. This information is output in units of seconds. If acquisition of the CPU time fails, unknown is displayed, as in [Sys:unknown]. This information is not output if the -XX:-HitachiVerboseGCCpuTime option is specified. If the status of Concurrent Marking is Concurrent Mark Start, 0 is output.

#:

The size is estimated by rounding up the area size to the size of one region, and represented as a multiple of the size of one region.

The following provides details about the causes of GC that are output for cause_info.

Table 7‒4: List of GC causes

Cause number	Cause content	Description	GC type
			Other than G1GC	G1GC
0	ObjAllocFail	GC occurred because the object area could not be allocated.	Y	Y
1	System.gc	GC occurred because the java.lang.System.gc method was called.	Y	Y
3	DelayedGC	GC that was suspended by JNI or JVMTI was started.	Y	Y
4	JavaGCCommand	GC occurred due to the javagc command.	Y	Y
6	JHeapProfCommand	GC occurred due to the jheapprof command.	Y	N
8	EMReclaimFail	Because objects were moved to the Java heap due to explicit release of Explicit memory, the Java heap overflowed.	Y	N
9	EMMigrateFail	Because objects were moved to the Java heap due to automatic release of Explicit memory, the Java heap overflowed.	Y	N
10	JVMTIForceGC	GC occurred due to the JVMTI function ForceGarbageCollection().	Y	Y
11	PromotionFail	GC occurred due to a CopyGC promotion failure.	Y	N
12	EMJavaGCCommand	GC occurred because an Explicit memory block was released by the javagc command.	Y	Y
13	EHeapProfCommand	GC occurred due to the eheapprof command.	Y	Y
14	G1HumAllocFail	When G1GC was used, GC occurred because a Humongous area was allocated.	N	Y
15	G1EvacuationPause	An evacuation occurred when G1GC was used.	N	Y
16	Concurrent Marking	No GC occurred but the Concurrent Marking processing, which stops and executes applications, was logged.	N	Y
17	EvacuationFail	When G1GC was used, GC occurred due to an evacuation failure.	N	Y
18	MetaspaceAllocFail	GC occurred because the Metaspace area could not be allocated.	Y	Y
19	LastMetaspaceGC	The last GC occurred before a Metaspace OutOfMemory error occurred.	Y	Y

Legend:

Y: Output.

N: Not output.

Syntax

-XX:[+|-]HitachiVerboseGC

Specifiable values

Type: String

-XX:+HitachiVerboseGC

Outputs the extended verbosegc information to the Java VM log file when GC occurs.

The information about each of the GC internal area types (Eden, Survivor, Tenured, and Metaspace) is output as the extended verbosegc information.

-XX:-HitachiVerboseGC

Does not output the extended verbosegc information to the Java VM log file when a GC occurs.

Default value

If the definition item is omitted:

-XX:-HitachiVerboseGC