最近Mongodb會經常突然掛掉，檢查日志發現如下的錯誤：

tcmalloc: large alloc 2061584302080 bytes == (nil) @
Tue Nov 26 17:45:04.539 out of memory, printing stack and exiting:
0xdddd81 0x6cfb4e 0x121021d 0xafcc1f 0xaf815f 0xaf8d1d 0xaf8e0f 0xaf52ae 0xaf53c9 0xb1eb11 0x8ab6a2 0x8d78ca 0x8d951d 0x8daa72 0xa80970 0xa8523c 0x9f9079 0x9fa5a3 0x6e8b88 0xdca34e
 ./mongod(_ZN5mongo15printStackTraceERSo+0x21) [0xdddd81]
 ./mongod(_ZN5mongo14my_new_handlerEv+0x3e) [0x6cfb4e]
 ./mongod(_Znwm+0x6d) [0x121021d]
 ./mongod(_ZNSt6vectorIN5mongo18DocumentSourceSort9KeyAndDocESaIS2_EE7reserveEm+0x6f) [0xafcc1f]
 ./mongod(_ZN5mongo18DocumentSourceSort12populateTopKEv+0x6f) [0xaf815f]
 ./mongod(_ZN5mongo18DocumentSourceSort8populateEv+0x2d) [0xaf8d1d]
 ./mongod(_ZN5mongo18DocumentSourceSort3eofEv+0xf) [0xaf8e0f]
 ./mongod(_ZN5mongo18DocumentSourceSkip7skipperEv+0x6e) [0xaf52ae]
 ./mongod(_ZN5mongo18DocumentSourceSkip3eofEv+0x9) [0xaf53c9]
 ./mongod(_ZN5mongo8Pipeline3runERNS_14BSONObjBuilderERSs+0x1b1) [0xb1eb11]
 ./mongod(_ZN5mongo15PipelineCommand3runERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x132) [0x8ab6a2]
 ./mongod(_ZN5mongo12_execCommandEPNS_7CommandERKSsRNS_7BSONObjEiRSsRNS_14BSONObjBuilderEb+0x3a) [0x8d78ca]
 ./mongod(_ZN5mongo7Command11execCommandEPS0_RNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x71d) [0x8d951d]
 ./mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x5f2) [0x8daa72]
 ./mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_11_BufBuilderINS_16TrivialAllocatorEEERNS_14BSONObjBuilderEbi+0x40) [0xa80970]
 ./mongod(_ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1_+0xd7c) [0xa8523c]
 ./mongod() [0x9f9079]
 ./mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_11HostAndPortE+0x383) [0x9fa5a3]
 ./mongod(_ZN5mongo16MyMessageHandler7processERNS_7MessageEPNS_21AbstractMessagingPortEPNS_9LastErrorE+0x98) [0x6e8b88]
 ./mongod(_ZN5mongo17PortMessageServer17handleIncomingMsgEPv+0x42e) [0xdca34e]