Pre-General Availability: 2017-05-23

A Fatal Error Log

Appendix describes the fatal error log, its location and contents.

The fatal error log is created when a fatal error occurs. It contains information and the state obtained at the time of the fatal error.


The format of this file can change slightly in update releases.

This appendix contains the following sections:

Location of Fatal Error Log

To specify where the log file will be created, use the product flag -XX:ErrorFile=file, where file represents the full path for the log file location.

The substring %% in the file variable is converted to %, and the substring %p is converted to the PID of the process.

In the following example, the error log file will be written to the directory /var/log/java and will be named java_errorpid.log:

java -XX:ErrorFile=/var/log/java/java_error%p.log

If the -XX:ErrorFile=file flag is not specified, the default log file name is hs_err_pid.log, where pid is the PID of the process.

In addition, if the -XX:ErrorFile=file flag is not specified, the system attempts to create the file in the working directory of the process. In the event that the file cannot be created in the working directory (insufficient space, permission problem, or other issue), the file is created in the temporary directory for the operating system. On Oracle Solaris and Linux operating systems the temporary directory is /tmp. On Windows the temporary directory is specified by the value of the TMP environment variable; if that environment variable is not defined, the value of the TEMP environment variable is used.

Description of Fatal Error Log

Description of the fatal error log file and the sections which contains information obtained at the time of the fatal error.

The Error log contains information obtained at the time of the fatal error, including the following information, where possible:

  • The operating exception or signal that provoked the fatal error

  • Version and configuration information

  • Details on the thread that provoked the fatal error and thread's stack trace

  • The list of running threads and their state

  • Summary information about the heap

  • The list of native libraries loaded

  • Command line arguments

  • Environment variables

  • Details about the operating system and CPU


In some cases only a subset of this information is output to the error log. This can happen when a fatal error is of such severity that the error handler is unable to recover and report all details.

The error log is a text file consisting of the following sections:


The format of the fatal error log described here is based on Java SE 6. The format might be different with other releases.

Header Format

The header section at the beginning of every fatal error log file contains a brief description of the problem.

The header is also printed to standard output and may show up in the application's output log.

The header includes a link to the HotSpot Virtual Machine Error Reporting Page, where the user can submit a bug report.

# An unexpected error has been detected by Java Runtime Environment:
#  SIGSEGV (0xb) at pc=0x417789d7, pid=21139, tid=1024
# Java VM: Java HotSpot(TM) Client VM (1.6.0-rc-b63 mixed mode, sharing)
# Problematic frame:
# C  []

# If you would like to submit a bug report, please visit:

The example above shows that the VM crashed on an unexpected signal.

The next line describes the signal type, program counter (pc) that caused the signal, process ID and thread ID, as shown in the following example.

#  SIGSEGV (0xb) at pc=0x417789d7, pid=21139, tid=1024
      |      |           |             |         +--- thread id
      |      |           |             +------------- process id
      |      |           +--------------------------- program counter
      |      |                                        (instruction pointer)
      |      +--------------------------------------- signal number
      +---------------------------------------------- signal name

The next line contains the VM version (Client VM or Server VM), an indication whether the application was run in mixed or interpreted mode, and an indication whether class file sharing was enabled as shown in the following line.

# Java VM: Java HotSpot(TM) Client VM (1.6.0-rc-b63 mixed mode, sharing)

The next information is the function frame that caused the crash, as shown in the following example.

# Problematic frame:
# C  []
  |              +-- Same as pc, but represented as library name and offset.
  |                  For position-independent libraries (JVM and most shared
  |                  libraries), it is possible to inspect the instructions
  |                  that caused the crash without a debugger or core file
  |                  by using a disassembler to dump instructions near the
  |                  offset.
  +----------------- Frame type

In this example, the "C" frame type indicates a native C frame. Table A-1 shows the possible frame types.

Table A-1 Frame Types

Frame Type Description


Native C frame


Interpreted Java frame


VM frame


VM-generated stub frame


Other frame types, including compiled Java frames

Internal errors will cause the VM error handler to generate a similar error dump. However, the header format is different. Examples of internal errors are guarantee() failure, assertion failure, ShouldNotReachHere(), and so forth. The following example shows the header format for an internal error.

# An unexpected error has been detected by HotSpot Virtual Machine:
# Internal Error (4F533F4C494E55583F491418160E43505000F5), pid=10226, tid=16384
# Java VM: Java HotSpot(TM) Client VM (1.6.0-rc-b63 mixed mode)

In the above header, there is no signal name or signal number. Instead the second line now contains Internal Error and a long hexadecimal string. This hexadecimal string encodes the source module and line number where the error was detected. In general this "error string" is useful only to engineers working on the HotSpot Virtual Machine.

The error string encodes a line number and therefore it changes with each code change and release. A crash with a given error string in one release (for example, 1.6.0) might not correspond to the same crash in an update release (for example, 1.6.0_01), even if the strings match.


Do not assume that a workaround or solution that worked in one situation associated with a given error string will work in another situation associated with that same error string. Note the following facts:

  • Errors with the same root cause might have different error strings.

  • Errors with the same error string might have completely different root causes.

Therefore, the error string should not be used as the sole criterion when troubleshooting bugs.

Thread Section Format

Information about the thread that crashed.

If multiple threads crash at the same time, only one thread is printed.

Thread Information

The first part of the thread section shows the thread that provoked the fatal error, as shown in the following example.

Current thread (0x0805ac88):  JavaThread "main" [_thread_in_native, id=21139]
                    |             |         |            |          +-- ID
                    |             |         |            +------------- state
                    |             |         +-------------------------- name
                    |             +------------------------------------ type
                    +-------------------------------------------------- pointer

The thread pointer is the pointer to the Java VM internal thread structure. It is generally of no interest unless you are debugging a live Java VM or core file.

The following list shows possible thread types.

  • JavaThread

  • VMThread

  • CompilerThread

  • GCTaskThread

  • WatcherThread

  • ConcurrentMarkSweepThread

Table A-2 shows the important thread states.

Table A-2 Thread States

Thread State Description


Thread is not created. This occurs only in the case of memory corruption.


Thread has been created but it has not yet started.


Thread is running native code. The error is probably a bug in native code.


Thread is running VM code.


Thread is running either interpreted or compiled Java code.


Thread is blocked.


If any of the above states is followed by the string _trans, that means that the thread is changing to a different state.

The thread ID in the output is the native thread identifier.

If a Java thread is a daemon thread, then the string daemon is printed before the thread state.

Signal Information

The next information in the error log describes the unexpected signal that caused the VM to terminate. On a Windows system the output appears as shown in the following example.

siginfo: ExceptionCode=0xc0000005, reading address 0xd8ffecf1

In the above example, the exception code is 0xc0000005 (ACCESS_VIOLATION), and the exception occurred when the thread attempted to read address 0xd8ffecf1.

On Oracle Solaris and Linux operating systems the signal number (si_signo) and signal code (si_code) are used to identify the exception, as follows:

siginfo:si_signo=11, si_errno=0, si_code=1, si_addr=0x00004321

Register Context

The next information in the error log shows the register context at the time of the fatal error. The exact format of this output is processor-dependent. The following example shows output for the Intel (IA32) processor.

EAX=0x00004321, EBX=0x41779dc0, ECX=0x080b8d28, EDX=0x00000000
ESP=0xbfffc1e0, EBP=0xbfffc1f8, ESI=0x4a6b9278, EDI=0x0805ac88
EIP=0x417789d7, CR2=0x00004321, EFLAGS=0x00010216

The register values might be useful when combined with instructions, as described below.

Machine Instructions

After the register values, the following example shows the error log that contains the top of stack followed by 32 bytes of instructions (opcodes) near the program counter (PC) when the system crashed. These opcodes can be decoded with a disassembler to produce the instructions around the location of the crash. Note: IA32 and AMD64 instructions are variable in length, and so it is not always possible to reliably decode instructions before the crash PC.

Top of Stack: (sp=0xbfffc1e0)
0xbfffc1e0:   00000000 00000000 0818d068 00000000
0xbfffc1f0:   00000044 4a6b9278 bfffd208 41778a10
0xbfffc200:   00004321 00000000 00000cd8 0818d328
0xbfffc210:   00000000 00000000 00000004 00000003
0xbfffc220:   00000000 4000c78c 00000004 00000000
0xbfffc230:   00000000 00000000 00180003 00000000
0xbfffc240:   42010322 417786ec 00000000 00000000
0xbfffc250:   4177864c 40045250 400131e8 00000000 
Instructions: (pc=0x417789d7)
0x417789c7:   ec 14 e8 72 ff ff ff 81 c3 f2 13 00 00 8b 45 08
0x417789d7:   0f b6 00 88 45 fb 8d 83 6f ee ff ff 89 04 24 e8

Thread Stack

Where possible, the next output in the error log is the thread stack, as shown in the following example. This includes the addresses of the base and the top of the stack, the current stack pointer, and the amount of unused stack available to the thread. This is followed, where possible, by the stack frames, and up to 100 frames are printed. For C/C++ frames the library name may also be printed. Note: In some fatal error conditions the stack may be corrupt, and in such case this detail may not be available.

Stack: [0x00040000,0x00080000),  sp=0x0007f9f8,  free space=254k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [jvm.dll+0x83d77]
C  [App.dll+0x1047]
j  Test.main([Ljava/lang/String;)V+0
v  ~StubRoutines::call_stub
V  [jvm.dll+0x80f13]
V  [jvm.dll+0xd3842]
V  [jvm.dll+0x80de4]
C  [java.exe+0x14c0]
C  [java.exe+0x64cd]
C  [kernel32.dll+0x214c7]

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j  Test.main([Ljava/lang/String;)V+0
v  ~StubRoutines::call_stub

The log contains two thread stacks.

  • The first thread stack is Native frames, which prints the native thread showing all function calls. However this thread stack does not take into account the Java methods that are inlined by the runtime compiler; if methods are inlined they appear to be part of the parent's stack frame.

    The information in the thread stack for native frames provides important information about the cause of the crash. By analyzing the libraries in the list from the top down, you can generally determine which library might have caused the problem and report it to the appropriate organization responsible for that library.

  • The second thread stack is Java frames, which prints the Java frames including the inlined methods, skipping the native frames. Depending on the crash it might not be possible to print the native thread stack but it might be possible to print the Java frames.

Further Details

If the error occurred in the VM thread or in a compiler thread, then further details may be seen from the following example. For example, in the case of the VM thread, the VM operation is printed if the VM thread is executing a VM operation at the time of the fatal error. In the following output example, the compiler thread provoked the fatal error. The task is a compiler task and the HotSpot Client VM is compiling method hs101t004Thread.ackermann.

Current CompileTask:
HotSpot Client Compiler:754   b  
nsk.jvmti.scenarios.hotswap.HS101.hs101t004Thread.ackermann(IJ)J (42 bytes)

For the HotSpot Server VM the output for the compiler task is slightly different but will also include the full class name and method.

Process Section Format

The process section is printed after the thread section.

It contains information about the whole process, including thread list and memory usage of the process.

Thread List

The thread list includes the threads that the VM is aware of, as shown in the following example.

=>0x0805ac88 JavaThread "main" [_thread_in_native, id=21139]
|      |         |        |             |             +----- ID
|      |         |        |             +------------------- state 
|      |         |        |                                  (JavaThread only)
|      |         |        +--------------------------------- name
|      |         +------------------------------------------ type
|      +---------------------------------------------------- pointer
+------------------------------------------------------ "=>" current thread

This includes all Java threads and some VM internal threads, but does not include any native threads created by the user application that have not attached to the VM a shown in the following example.

Java Threads: ( => current thread )
  0x080c8da0 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=21147]
  0x080c7988 JavaThread "CompilerThread0" daemon [_thread_blocked, id=21146]
  0x080c6a48 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=21145]
  0x080bb5f8 JavaThread "Finalizer" daemon [_thread_blocked, id=21144]
  0x080ba940 JavaThread "Reference Handler" daemon [_thread_blocked, id=21143]
=>0x0805ac88 JavaThread "main" [_thread_in_native, id=21139]

Other Threads:
  0x080b6070 VMThread [id=21142]
  0x080ca088 WatcherThread [id=21148]

The thread type and thread state are described in Thread Section Format.

VM State

The next information is the VM state, which indicates the overall state of the virtual machine. Table A-3 describes the general states.

Table A-3 VM States

General VM State Description

not at a safepoint

Normal execution.

at safepoint

All threads are blocked in the VM waiting for a special VM operation to complete.


A special VM operation is required and the VM is waiting for all threads in the VM to block.

The VM state output is a single line in the error log, as follows:

VM state:not at safepoint (normal execution)

Mutexes and Monitors

The next information in the error log is a list of mutexes and monitors that are currently owned by a thread, as shown in the following example. These mutexes are VM internal locks rather than monitors associated with Java objects. Below is an example to show how the output might look when a crash happens when VM locks are held. For each lock the log contains the name of the lock, its owner, and the addresses of a VM internal mutex structure and its OS lock. In general this information is useful only to those who are very familiar with the HotSpot VM. The owner thread can be cross-referenced to the thread list.

VM Mutex/Monitor currently owned by a thread:  
([mutex/lock_event])[0x007357b0/0x0000031c] Threads_lock - owner thread: 0x00996318
[0x00735978/0x000002e0] Heap_lock - owner thread: 0x00736218

Heap Summary

The next information is a summary of the heap, as shown in the following example. The output depends on the garbage collection (GC) configuration. In this example the serial collector is used, class data sharing is disabled, and the tenured generation is empty. This probably indicates that the fatal error occurred early or during start-up and a GC has not yet promoted any objects into the tenured generation.

 def new generation   total 576K, used 161K [0x46570000, 0x46610000, 0x46a50000)  
  eden space 512K,  31% used [0x46570000, 0x46598768, 0x465f0000)
  from space 64K,   0% used [0x465f0000, 0x465f0000, 0x46600000)
  to   space 64K,   0% used [0x46600000, 0x46600000, 0x46610000)
 tenured generation   total 1408K, used 0K [0x46a50000, 0x46bb0000, 0x4a570000)
   the space 1408K,   0% used [0x46a50000, 0x46a50000, 0x46a50200, 0x46bb0000)
 compacting perm gen  total 8192K, used 1319K [0x4a570000, 0x4ad70000, 0x4e570000)
   the space 8192K,  16% used [0x4a570000, 0x4a6b9d48, 0x4a6b9e00, 0x4ad70000)
No shared spaces configured.

Memory Map

The next information in the log is a list of virtual memory regions at the time of the crash. This list can be long in the case of large applications. The memory map can be very useful when debugging some crashes, as it can tell you what libraries are actually being used, their location in memory, as well as the location of heap, stack, and guard pages.

The format of the memory map is operating-system-specific. On the Oracle Solaris operating system, the base address and library name are printed. On the Linux system the process memory map (/proc/pid/maps) is printed. On the Windows system, the base and end addresses of each library are printed. The following example shows the output generated on Linux/x86.


Most of the lines have been omitted from the example for the sake of brevity.
Dynamic libraries:
08048000-08056000 r-xp 00000000 03:05 259171     /h/jdk6/bin/java
08056000-08058000 rw-p 0000d000 03:05 259171     /h/jdk6/bin/java
08058000-0818e000 rwxp 00000000 00:00 0
40000000-40013000 r-xp 00000000 03:0a 400046     /lib/
40013000-40014000 rw-p 00013000 03:0a 400046     /lib/
40014000-40015000 r--p 00000000 00:00 0
Lines omitted.
4123d000-4125a000 rwxp 00001000 00:00 0
4125a000-4125f000 rwxp 00000000 00:00 0
4125f000-4127b000 rwxp 00023000 00:00 0
4127b000-4127e000 ---p 00003000 00:00 0
4127e000-412fb000 rwxp 00006000 00:00 0
412fb000-412fe000 ---p 00083000 00:00 0
412fe000-4137b000 rwxp 00086000 00:00 0
Lines omitted.
44600000-46570000 rwxp 00090000 00:00 0
46570000-46610000 rwxp 00000000 00:00 0
46610000-46a50000 rwxp 020a0000 00:00 0
46a50000-46bb0000 rwxp 00000000 00:00 0
46bb0000-4a570000 rwxp 02640000 00:00 0
Lines omitted.

The following is a format of memory map in the error log.

40049000-4035c000 r-xp 00000000 03:05 824473 /jdk1.5/jre/lib/i386/client/
|<------------->|  ^      ^       ^     ^    |<--------------------------------->|
  Memory region    |      |       |     |                      |
                   |      |       |     |                      |
  Permission   --- +      |       |     |                      |
    r: read               |       |     |                      |
    w: write              |       |     |                      |
    x: execute            |       |     |                      |
    p: private            |       |     |                      |
    s: share              |       |     |                      |
                          |       |     |                      |
  File offset   ----------+       |     |                      |
                                  |     |                      |
  Major ID and minor ID of -------+     |                      |
  the device where the file             |                      |
  is located (i.e. /dev/hda5)           |                      |
                                        |                      |
  inode number  ------------------------+                      |
  File name  --------------------------------------------------+

The above example shows the memory map output, each library has two virtual memory regions: one for code and one for data. The permission for the code segment is marked with r-xp (readable, executable, private), and the permission for the data segment is rw-p (readable, writable, private).

The Java heap is already included in the heap summary earlier in the output, but it can be useful to verify that the actual memory regions reserved for heap match the values in the heap summary and that the attributes are set to rwxp.

Thread stacks usually show up in the memory map as two back-to-back regions, one with permission ---p (guard page) and one with permission rwxp (actual stack space). In addition, it is useful to know the guard page size or stack size. For example, in this memory map, the stack is located from 4127b000 to 412fb000.

On a Windows system, the memory map output is the load and end address of each loaded module, as shown in the following example.

Dynamic libraries:
0x00400000 - 0x0040c000     c:\jdk6\bin\java.exe
0x77f50000 - 0x77ff7000     C:\WINDOWS\System32\ntdll.dll
0x77e60000 - 0x77f46000     C:\WINDOWS\system32\kernel32.dll
0x77dd0000 - 0x77e5d000     C:\WINDOWS\system32\ADVAPI32.dll
0x78000000 - 0x78087000     C:\WINDOWS\system32\RPCRT4.dll
0x77c10000 - 0x77c63000     C:\WINDOWS\system32\MSVCRT.dll
0x08000000 - 0x08183000     c:\jdk6\jre\bin\client\jvm.dll
0x77d40000 - 0x77dcc000     C:\WINDOWS\system32\USER32.dll
0x7e090000 - 0x7e0d1000     C:\WINDOWS\system32\GDI32.dll
0x76b40000 - 0x76b6c000     C:\WINDOWS\System32\WINMM.dll
0x6d2f0000 - 0x6d2f8000     c:\jdk6\jre\bin\hpi.dll
0x76bf0000 - 0x76bfb000     C:\WINDOWS\System32\PSAPI.DLL
0x6d680000 - 0x6d68c000     c:\jdk6\jre\bin\verify.dll
0x6d370000 - 0x6d38d000     c:\jdk6\jre\bin\java.dll
0x6d6a0000 - 0x6d6af000     c:\jdk6\jre\bin\zip.dll
0x10000000 - 0x10032000     C:\bugs\crash2\App.dll

VM Arguments and Environment Variables

The next information in the error log is a list of VM arguments, followed by a list of environment variables, as shown in the following example.

VM Arguments:
java_command: NativeSEGV 2

Environment Variables:


The list of environment variables is not the full list but rather a subset of the environment variables that are applicable to the Java VM.

Signal Handlers

On Oracle Solaris and Linux operating systems, the next information in the error log is the list of signal handlers, as shown in the following example.

Signal Handlers:
SIGSEGV: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGBUS: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGFPE: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGPIPE: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGILL: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGUSR1: SIG_DFL, sa_mask[0]=0x00000000, sa_flags=0x00000000
SIGUSR2: [], sa_mask[0]=0x80000000, sa_flags=0x10000004
SIGHUP: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGINT: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGQUIT: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGTERM: [], sa_mask[0]=0xfffbfeff, sa_flags=0x10000004
SIGUSR2: [], sa_mask[0]=0x80000000, sa_flags=0x10000004

System Section Format

The final section in the error log is the system information. The output is operating-system-specific but in general includes the operating system version, CPU information, and summary information about the memory configuration.

The following example shows output on a Linux operating system.

---------------  S Y S T E M  ---------------

uname:Linux 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64
libc:glibc 2.15 NPTL 2.15 
rlimit: STACK 8192k, CORE infinity, NPROC 1160369, NOFILE 4096, AS infinity
load average:0.46 0.33 0.27

MemTotal:       148545440 kB
MemFree:         1020964 kB
Buffers:        29600728 kB
Cached:         86607768 kB
SwapCached:        16112 kB
Active:         52272944 kB
Inactive:       64862992 kB
Active(anon):     314080 kB
Inactive(anon):   616296 kB
Active(file):   51958864 kB
Inactive(file): 64246696 kB
Unevictable:          16 kB
Mlocked:              16 kB
SwapTotal:       1051644 kB
SwapFree:         976092 kB
Dirty:                40 kB
Writeback:             0 kB
AnonPages:        912404 kB
Mapped:            95804 kB
Shmem:              2936 kB
Slab:           28625980 kB
SReclaimable:   28337400 kB
SUnreclaim:       288580 kB
KernelStack:        6040 kB
PageTables:        42524 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    75324364 kB
Committed_AS:    6172612 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      681668 kB
VmallocChunk:   34282379392 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      171520 kB
DirectMap2M:     8208384 kB
DirectMap1G:    142606336 kB

CPU:total 24 (initial active 24) (6 cores per cpu, 2 threads per core) family 6 model 44 stepping 2, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, aes, clmul, ht, tsc, tscinvbit, tscinv
CPU Model and flags from /proc/cpuinfo:
model name      : Intel(R) Xeon(R) CPU           X5675  @ 3.07GHz
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 popcnt aes lahf_lm ida arat epb dts tpr_shadow vnmi flexpriority ept vpid

Memory: 4k page, physical 148545440k(1020964k free), swap 1051644k(976092k free)

vm_info: Java HotSpot(TM) 64-Bit Server VM (9-ea+167) for linux-amd64 JRE (9-ea+167), built on Apr 27 2017 00:28:45 by "javare" with gcc 4.9.2

On Oracle Solaris and Linux, the operating system information is contained in the file /etc/*release. This file describes the kind of system the application is running on, and in some cases the information string might include the patch level. Some system upgrades are not reflected in the /etc/*release file. This is especially true on the Linux system, where the user can rebuild any part of the system.

On Oracle Solaris operating system the uname system call is used to get the name for the kernel. The thread library (T1 or T2) is also printed.

On the Linux system the uname system call is also used to get the kernel name. The libc version and the thread library type are also printed, as shown in the following example.

uname:Linux 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64
libc:glibc 2.15           NPTL 2.15 
    |<- glibc version ->|<--  pthread type       -->|

On Linux there are three possible thread types, namely linuxthreads (fixed stack), linuxthreads (floating stack), and NPTL. They are normally installed in /lib, /lib/i686, and /lib/tls.

It is useful to know the thread type. For example, if the crash appears to be related to pthread, then you might be able to work around the issue by selecting a different pthread library. A different pthread library (and libc) can be selected by setting LD_LIBRARY_PATH or LD_ASSUME_KERNEL.

The glibc version usually does not include the patch level. The command rpm -q glibc might provide more detailed version information.

On Oracle Solaris and Linux operating systems, the next information is the rlimit information.


The default stack size of the VM is usually smaller than the system limit, as shown in the following example.
rlimit: STACK 8192k, CORE infinity, NPROC 1160369, NOFILE 4096, AS infinity
             |          |                  |           |           virtual memory (-v)
             |          |                  |           +--- max open files (ulimit -n)
             |          |                  +----------- max user processes (ulimit -u)
             |          +------------------------------ core dump size (ulimit -c)
             +----------------------------------------- stack size (ulimit -s)
load average:0.04 0.05 0.02
rlimit: STACK 8192k, CORE 0k, NPROC 4092, NOFILE 1024, AS infinity
             |          |         |           |           virtual memory (-v)
             |          |         |           +--- max open files (ulimit -n)
             |          |         +----------- max user processes (ulimit -u)
             |          +------------------------- core dump size (ulimit -c)
             +---------------------------------------- stack size (ulimit -s)
load average:0.04 0.05 0.02

The next information specifies the CPU architecture and capabilities identified by the VM at start-up, as shown in the following example.

CPU:total 24 (initial active 24) (6 cores per cpu, 2 threads per core) family 6 model 44 stepping 2, cmov, cx8, fxsr, mmx
          |                                                                   |                      | |<----- CPU features ---->|
          |                                                                   |
          |                                                                   +--- processor family (IA32 only):
          |                                                                   3 - i386
          |                                                                   4 - i486
          |                                                                   5 - Pentium
          |                                                                   6 - PentiumPro, PII, PIII
          |                                                                   15 - Pentium 4
          +------------ Total number of CPUs

Table A-4 shows the possible CPU features on a SPARC system.

Table A-4 SPARC Features

SPARC Feature Description


Supports v8 instructions.


Supports v9 instructions.


Supports visualization instructions.


Supports visualization instructions.


UltraSparc III.


No hardware integer multiply and divide.


No multiply-add and multiply-subtract instructions.

Table A-5 shows the possible CPU features on an Intel/IA32 system.

Table A-5 Intel/IA32 Features

Intel/IA32 Feature Description


Supports cmov instruction.


Supports cmpxchg8b instruction.


Supports fxsave and fxrstor.


Supports MMX.


Supports SSE extensions.


Supports SSE2 extensions.


Supports Hyper-Threading Technology.

Table A-6 shows the possible CPU features on an AMD64/EM64T system.

Table A-6 AMD64/EM64T Features

AMD64/EM64T Feature Description


AMD Opteron, Athlon64, and so forth.


Intel EM64T processor.


Supports 3DNow extension.


Supports Hyper-Threading Technology.

The next information in the error log is memory information, as shown in the following example.

                                                  unused swap space
                              total amount of swap space        |
                   unused physical memory            |          |
total amount of physical memory       |              |          |
     page size              |         |              |          |
           v                v         v              v          v
Memory: 4k page, physical 513604k(11228k free), swap 530104k(497504k free)

Some systems require swap space to be at lease twice the size of real physical memory, whereas other systems do not have any such requirements. As a general rule, if both physical memory and swap space are almost full, there is good reason to suspect that the crash was due to insufficient memory.

On Linux systems the kernel may convert most of unused physical memory to file cache. When there is a need for more memory, the Linux kernel will give the cache memory back to the application. This is handled transparently by the kernel, but it does mean the amount of unused physical memory reported by fatal error handler could be close to zero when there is still sufficient physical memory available.

The final information in the SYSTEM section of the error log is vm_info, which is a version string embedded in Every Java VM has its own unique vm_info string. If you are in doubt about whether the fatal error log was generated by a particular Java VM, check the version string.