why Mongodb can not kill inactive operation?

陆峰

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Sep 16, 2013, 5:46:38 AM9/16/13

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I want to kill some inactive operations, operation information like this

                {
                        "opid" : 231889001,
                        "active" : false,
                        "op" : "query",
                        "ns" : "test.info",
                        "query" : {
                                "_id" : {
                                        "$in" : [
                                                "abc",
                                                "efg",
                                        ]
                                }
                        },
                        "client" : "192.168.0.114:47274",
                        "desc" : "conn560",
                        "threadId" : "0x7f83d5138700",
                        "connectionId" : 560,
                        "waitingForLock" : false,
                        "killPending" : true,
                        "numYields" : 0,
                        "lockStats" : {
                                "timeLockedMicros" : {
                                        "r" : NumberLong(365),
                                        "w" : NumberLong(0)
                                },
                                "timeAcquiringMicros" : {
                                        "r" : NumberLong(2),
                                        "w" : NumberLong(0)
                                }
                        }
                }

and I use this command to kill this operation

> db.killOp(231889001)
{ "info" : "attempting to kill op" }

It seem not take any effect, this operation is still here.

and I also check the read/write queue and currentOp(), did not find any command in queue and currentOp() is empty.

        "globalLock": {
            "lockTime": 130560173,
            "currentQueue": {
                "total": 0,
                "writers": 0,
                "readers": 0
            },
            "activeClients": {
                "total": 0,
                "writers": 0,
                "readers": 0
            },
            "totalTime": 282024131000
        },

> db.currentOp()
{ "inprog" : [ ] }

Question is:

1. if I want to kill these operations, what can I do? except restart MongoDB server.

2. Why there are so may operations are inactive? what has caused this problem?

Thanks.

Jeff Lee

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Sep 16, 2013, 1:54:37 PM9/16/13

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Do you have a lot of open cursors? I believe they'll show up as inactive in db.currentOp(1) until you close them.

Kristina Chodorow did a good write-up on killing ops a while back.

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陆峰

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Sep 16, 2013, 10:26:55 PM9/16/13

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the highest is less than 10 cursors in server. currently there is nothing cursor in server but these operations still inactive and can not killed.

I check the document and she said one that die when they yield whatever lock they're holding, this means that if the op never yields (note that numYields is 0 in the example above), it will never be killed. Maybe current operations in my MongoDB is dead, it will never be killed.

and Does this inactive operations ( never be killed) will occupy some of the space in hashtable in MongoDB? Is this a bug and I can open a Jira in MongoDB.