MongDB内存消耗高于wiredTigercacheSizeGB中设置的值

Question

各位专家您好

我有一个mongodb服务器在我的2GB ec2实例上运行，使用以下命令

mongod--wiredTigerCacheSizeGB=0.5

以下是我的内存使用情况：

------------------------------------------------
MALLOC:      509658616 (  486.0 MiB) Bytes in use by application
MALLOC: +    100265984 (   95.6 MiB) Bytes in page heap freelist
MALLOC: +     10784344 (   10.3 MiB) Bytes in central cache freelist
MALLOC: +      8235328 (    7.9 MiB) Bytes in transfer cache freelist
MALLOC: +      3289712 (    3.1 MiB) Bytes in thread cache freelists
MALLOC: +      4063232 (    3.9 MiB) Bytes in malloc metadata
MALLOC:   ------------
MALLOC: =    636297216 (  606.8 MiB) Actual memory used (physical + swap)
MALLOC: +       385024 (    0.4 MiB) Bytes released to OS (aka unmapped)
MALLOC:   ------------
MALLOC: =    636682240 (  607.2 MiB) Virtual address space used
MALLOC:
MALLOC:          23555              Spans in use
MALLOC:             26              Thread heaps in use
MALLOC:           4096              Tcmalloc page size
------------------------------------------------

根据我的理解使用的虚拟地址空间是Mongodb占用的总内存。如果有人能告诉我为什么它会增加到0.5(500MB(的极限以上，那将是非常有帮助的

----------------More  Info--------------------
{
"name" : "wiredTiger",
"supportsCommittedReads" : true,
"oldestRequiredTimestampForCrashRecovery" : Timestamp(0, 0),
"supportsPendingDrops" : true,
"dropPendingIdents" : NumberLong(0),
"supportsSnapshotReadConcern" : true,
"readOnly" : false,
"persistent" : true,
"backupCursorOpen" : false
}
{
"db" : "Database",
"collections" : 43,
"views" : 0,
"objects" : 2780441,
"avgObjSize" : 2756.87204116182,
"dataSize" : 7665320055.0,
"storageSize" : 2320449536.0,
"numExtents" : 0,
"indexes" : 58,
"indexSize" : 156573696.0,
"scaleFactor" : 1.0,
"fsUsedSize" : 77780537344.0,
"fsTotalSize" : 214746263552.0,
"ok" : 1.0
}

MongDB内存消耗高于wiredTigercacheSizeGB 中的设置值

Answer 1

Wired tiger是MongoDB的一个组件。还有许多其他组件。预计整个服务器的内存使用量将大于对服务器的一个组件的一个方面施加的限制。