# Problematic frame:
# V [libjvm.so+0x68fddb] java_lang_Class::signers(oopDesc*)+0x1b
一般当前线程是crash的直接原因，可以看出它就是虚拟机线程，这次崩之前应用记录了out of memory
Current thread (0x00007fa3a00b5800): VMThread [stack: 0x00007fa390cd7000,0x00007fa390dd8000] [id=19257]
崩的时候线程栈里的操作都是虚拟机的，正在打Dump这是。。。，打Dump打崩了？
Stack: [0x00007fa390cd7000,0x00007fa390dd8000], sp=0x00007fa390dd6720, free space=1021k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x68fddb] java_lang_Class::signers(oopDesc*)+0x1b
V [libjvm.so+0x61c072] DumperSupport::dump_class_and_array_classes(DumpWriter*, Klass*)+0xb2
V [libjvm.so+0x467a86] ClassLoaderDataGraph::classes_do(void (*)(Klass*))+0x36
V [libjvm.so+0x61f4ce] VM_HeapDumper::doit()+0x23e
V [libjvm.so+0xac55d5] VM_Operation::evaluate()+0x55
V [libjvm.so+0xac39aa] VMThread::evaluate_operation(VM_Operation*)+0xba
V [libjvm.so+0xac3d2e] VMThread::loop()+0x1ce
V [libjvm.so+0xac41a0] VMThread::run()+0x70
V [libjvm.so+0x91ef78] java_start(Thread*)+0x108
VM_Operation (0x00007fa32b7f66a0): HeapDumper, mode: safepoint, requested by thread 0x00007fa32c039800
RAX=0x0000000000000040 is an unknown value
RBX=0x00007fa32b7f6730 is pointing into the stack for thread: 0x00007fa32c039800
RCX=0x00007fa30adfd010 is an unknown value
RDX=0x0000000000000000 is an unknown value
RSP=0x00007fa390dd6720 is an unknown value
RBP=0x00007fa390dd6720 is an unknown value
RSI=0x0000000000000000 is an unknown value
RDI=0x0000000000000000 is an unknown value
R8 =0x0000000000000000 is an unknown value
R9 =0x000000000000002a is an unknown value
R10=0x0000000000000000 is an unknown value
R11=0x00007fa3a7b3db20: <offset 0x63db20> in /usr/local/jdk1.8.0_91/jre/lib/amd64/server/libjvm.so at 0x00007fa3a7500000
R12=0x00007fa3a7b1c420: <offset 0x61c420> in /usr/local/jdk1.8.0_91/jre/lib/amd64/server/libjvm.so at 0x00007fa3a7500000
R13=0x00000001009e1dc8 is pointing into metadata
R14=0x00007fa390dd673c is an unknown value
R15=0x00007fa32b7f66a0 is pointing into the stack for thread: 0x00007fa32c039800
Other Threads:
=>0x00007fa3a00b5800 VMThread [stack: 0x00007fa390cd7000,0x00007fa390dd8000] [id=19257]
0x00007fa3a010b000 WatcherThread [stack: 0x00007fa381eff000,0x00007fa382000000] [id=19266]
在安全点，这说明在GC，同时大量线程都在block也证明了这一点，Stop了The World
VM state:at safepoint (normal execution)
VM Mutex/Monitor currently owned by a thread: ([mutex/lock_event])
[0x00007fa3a0006ac0] Threads_lock - owner thread: 0x00007fa3a00b5800
[0x00007fa3a0007040] Heap_lock - owner thread: 0x00007fa32c039800
Heap:
par new generation total 306688K, used 306687K [0x00000000c0000000, 0x00000000d4cc0000, 0x00000000d4cc0000)
eden space 272640K, 100% used [0x00000000c0000000, 0x00000000d0a40000, 0x00000000d0a40000)
from space 34048K, 99% used [0x00000000d2b80000, 0x00000000d4cbfc20, 0x00000000d4cc0000)
to space 34048K, 0% used [0x00000000d0a40000, 0x00000000d0a40000, 0x00000000d2b80000)
concurrent mark-sweep generation total 707840K, used 707839K [0x00000000d4cc0000, 0x0000000100000000, 0x0000000100000000)
Metaspace used 55241K, capacity 60784K, committed 61032K, reserved 1099776K
class space used 8809K, capacity 10268K, committed 10404K, reserved 1048576K
Card table byte_map: [0x00007fa3a60c7000,0x00007fa3a62c8000] byte_map_base: 0x00007fa3a5ac7000
Marking Bits: (CMSBitMap*) 0x00007fa3a0061848
Bits: [0x00007fa3a509b000, 0x00007fa3a5b68000)
Mod Union Table: (CMSBitMap*) 0x00007fa3a0061908
Bits: [0x00007fa3a506f000, 0x00007fa3a509a340)
Polling page: 0x00007fa3a8703000
CodeCache: size=245760Kb used=47105Kb max_used=47139Kb free=198654Kb
bounds [0x00007fa391000000, 0x00007fa393e70000, 0x00007fa3a0000000]
total_blobs=11243 nmethods=10606 adapters=550
compilation: enabled
各种block，没什么看头
identity_map_codec.rb:51" daemon [_thread_blocked, id=19284, stack(0x00007fa32b1f8000,0x00007fa32b3f9000)]
0x00007fa32c03a800 JavaThread "[main]<file" daemon [_thread_blocked, id=19283, stack(0x00007fa32b3f9000,0x00007fa32b5fa000)]
0x00007fa32c039800 JavaThread "[main]<file" daemon [_thread_blocked, id=19282, stack(0x00007fa32b5fa000,0x00007fa32b7fb000)]
0x00007fa32c038000 JavaThread "[main]<file" daemon [_thread_blocked, id=19281, stack(0x00007fa32b7fc000,0x00007fa32b9fd000)]
0x00007fa32c036800 JavaThread "[main]<file" daemon [_thread_blocked, id=19280, stack(0x00007fa32b9fd000,0x00007fa32bbfe000)]
0x00007fa32c02b800 JavaThread "[main]<file" daemon [_thread_blocked, id=19279, stack(0x00007fa32bbfe000,0x00007fa32bdff000)]
0x00007fa32c025800 JavaThread "[main]<file" daemon [_thread_blocked, id=19278, stack(0x00007fa32bdff000,0x00007fa32c000000)]
0x00007fa32c023000 JavaThread "[main]<file" daemon [_thread_blocked, id=19277, stack(0x00007fa360119000,0x00007fa36031a000)]
0x00007fa334002800 JavaThread "[main]-pipeline-manager" daemon [_thread_blocked, id=19276, stack(0x00007fa36031a000,0x00007fa36051b000)]
0x00007fa340001000 JavaThread "pool-2-thread-1" [_thread_blocked, id=19275, stack(0x00007fa36051b000,0x00007fa36071c000)]
这应该是说，GC的时候报了内存溢出，溢出的时候要打个Dump，然而IO超时，于是就崩了，就崩了(╯‵□′)╯︵┻━┻
Internal exceptions (10 events):
Event: 3175189.838 Thread 0x00007fa32c1ee800 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c1bde570) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175190.227 Thread 0x00007fa32c1f0800 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c1e0def8) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175205.591 Thread 0x00007fa32c1ee000 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c2c114e0) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175206.057 Thread 0x00007fa32c1f0800 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c32ddfd0) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175210.248 Thread 0x00007fa32c1ee000 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c013b2b8) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175215.785 Thread 0x00007fa32c1f0800 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000c0664360) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175220.940 Thread 0x00007fa340006800 Implicit null exception at 0x00007fa39157ea7f to 0x00007fa39157f395
Event: 3175221.675 Thread 0x00007fa32c1ee000 Exception <a 'java/net/SocketTimeoutException': Read timed out> (0x00000000d4c8ebf8) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u91/6644/hotspot/src/share/vm/prims/jni.cpp, line 735]
Event: 3175225.052 Thread 0x00007fa32c025800 Implicit null exception at 0x00007fa3922e05f9 to 0x00007fa3922e1fb5
Event: 3175225.052 Thread 0x00007fa340001000 Implicit null exception at 0x00007fa393615368 to 0x00007fa393615bbd
Events (10 events):
Event: 3175226.764 Executing VM operation: GenCollectForAllocation done
Event: 3175226.764 Executing VM operation: GenCollectForAllocation
Event: 3175227.434 Executing VM operation: GenCollectForAllocation done
Event: 3175227.434 Executing VM operation: GenCollectForAllocation
Event: 3175228.091 Executing VM operation: GenCollectForAllocation done
Event: 3175228.091 Executing VM operation: GenCollectForAllocation
Event: 3175228.762 Executing VM operation: GenCollectForAllocation done
Event: 3175228.762 Executing VM operation: GenCollectForAllocation
Event: 3175229.256 Executing VM operation: GenCollectForAllocation done
Event: 3175229.256 Executing VM operation: HeapDumper
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