5.8.2 When C Heap Is Insufficient

When C heap is insufficient, the message output, and dump output or core dump generation is performed in the following order:

A message log indicating insufficient C heap is output to the error report file and standard output.
If the memory is insufficient during the execution of 1., a simple message is output to the standard output.
In UNIX, if the memory is still insufficient during the output of a simple message, output of the message and error log file is interrupted and a core dump is generated.

Each output format is described below.

Organization of this subsection

(1) Output contents of a message log indicating insufficient C heap
(2) Output contents of message showing memory insufficiency
(3) Output contents of the message indicating core dump generation

(1) Output contents of a message log indicating insufficient C heap

The output format of a message log indicating insufficient C heap is described below. This format is common for the error report file and standard output.

In Windows

Exception in thread <ThreadName> java.lang.OutOfMemoryError:requested <n> bytes [ for <message>].
 
Memory Status
-------------
       Memory in use: utilization-rate%
       Physical memory: free-memory-size/total-memory-sizefree
       Virtual memory: free-memory-size/Total-memory-sizefree
       Paging file: free-volume/total-volumefree
 
Heap Status
-----------
Java-heap-information
-----------
Stack Trace
-----------
stack-trace
JVM Internal Memory Status
--------------------------
area-information-managed-by-the-unique-memory-management-function
Insufficient memory for malloc. JVM generates core file.
-----------

In AIX or Linux

Exception in thread <ThreadName> java.lang.OutOfMemoryError: requested <n> bytes [for <message>].
 
Memory Status
-------------
 maximum size of data segment
 soft(current) limit: software-limit-value-acquired-by-getrlimit(RLIMIT_DATA) kbytes (Hexadecimal)
 hard limit: hardware-limit-value-acquired-by-getrlimit(RLIMIT_DATA) kbytes (Hexadecimal)
 current end of the heap: value-acquired-by-sbrk(0)
 JVM allocation size by malloc: memory-size-allocated-to-JavaVM kbytes (Hexadecimal)
 malloc information
     total space in arena            :mallinfo.arena value
     number of ordinary blocks       :mallinfo.ordblks value
     number of small blocks          :mallinfo.smblks value
     number of holding blocks        :mallinfo.hblks value
     space in holding block headers  :mallinfo.hblkhd value
     space in small blocks in use    :mallinfo.usmblks value
     space in free small blocks      :mallinfo.fsmblks value
     space in ordinary blocks in use :mallinfo.uordblks value
     space in free ordinary blocks   :mallinfo.fordblks value
     cost of enabling keep option    :mallinfo.keepcost value
 
Heap Status
-----------
Java-heap-information
-----------
Stack Trace
-----------
stack-trace
-----------
 
JVM Internal Memory Status
--------------------------
area-information-managed-by-the-unique-memory-management-function

When such a message is output, take appropriate measures such as reducing C heap.

The output contents are as follows:

Table 5‒26: Output items of message log when C heap is insufficient
Output items	Description
ThreadName	The thread name extracted by the `Thread#getName()` method is output.
n	The size of memory securing requests is output.
message	The internal message required by maintenance personnel for investigation is output. In some cases it may not be output.
Java heap information	The usage status of Java heap is output.
Stack trace	The stack trace is output when the thread for which the memory is insufficient is the thread that is executing a Java code. The stack trace is not output when the memory is insufficient in the thread that is executing internal process such as compilation process in JavaVM.

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(2) Output contents of message showing memory insufficiency

If memory becomes insufficient while a message log indicating insufficient C heap is being output, the process cannot be continued. In this case, a simple message in the following format is output to the standard output.

java.lang.OutOfMemoryError:requested <n> bytes for <message>

The output contents are as follows:

Table 5‒27: Output contents of a simple message when the memory is insufficient
Output items	Description
n	The size of memory securing requests is output.
message	The internal message required by maintenance personnel for investigation is output.

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(3) Output contents of the message indicating core dump generation

If the memory is still insufficient when a simple message is output, output of the message and error log file is interrupted and a core dump is generated. When a core dump is generated, the message in the following format is output in the standard output.

Can't create logs because of memory shortage.
Insufficient memory for malloc. JVM generates core file

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