mongodb锁

锁住写操作

> db.fsyncLock();
{
        "info" : "now locked against writes, use db.fsyncUnlock() to unlock",
        "lockCount" : NumberLong(1),
        "seeAlso" : "http://dochub.mongodb.org/core/fsynccommand",
        "ok" : 1
}
> db.currentOp()
{
        "inprog" : [
                {
                        "desc" : "conn10",
                        "threadId" : "140688623027968",
                        "connectionId" : 10,
                        "client" : "127.0.0.1:40943",
                        "appName" : "MongoDB Shell",
                        "active" : true,
                        "opid" : 6757,
                        "secs_running" : 0,
                        "microsecs_running" : NumberLong(27),
                        "op" : "command",
                        "ns" : "admin.$cmd",
                        "query" : {
                                "currentOp" : 1
                        },
                        "numYields" : 0,
                        "locks" : {

                        },
                        "waitingForLock" : false,
                        "lockStats" : {

                        }
                },
                {
                        "desc" : "conn8",
                        "threadId" : "140688851060480",
                        "connectionId" : 8,
                        "client" : "172.16.160.92:39130",
                        "active" : true,
                        "opid" : 6755,
                        "secs_running" : 0,
                        "microsecs_running" : NumberLong(867788),
                        "op" : "getmore",
                        "ns" : "local.oplog.$main",
                        "query" : {
                                "ts" : {
                                        "$gte" : Timestamp(1512120014, 1)
                                }
                        },
                        "planSummary" : "COLLSCAN",
                        "numYields" : 0,
                        "locks" : {

                        },
                        "waitingForLock" : false,
                        "lockStats" : {
                                "Global" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(2)
                                        }
                                },
                                "Database" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(1)
                                        }
                                },
                                "Collection" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(1)
                                        }
                                }
                        }
                },
                {
                        "desc" : "fsyncLockWorker",
                        "threadId" : "140688631420672",
                        "active" : true,
                        "opid" : 6719,
                        "op" : "none",
                        "ns" : "",
                        "query" : {

                        },
                        "numYields" : 0,
                        "locks" : {
                                "Global" : "R"
                        },
                        "waitingForLock" : false,
                        "lockStats" : {
                                "Global" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(1),
                                                "R" : NumberLong(1),
                                                "W" : NumberLong(1)
                                        }
                                }
                        }
                },
                {
                        "desc" : "WT RecordStoreThread: local.oplog.$main",
                        "threadId" : "140688725845760",
                        "active" : true,
                        "opid" : 5,
                        "secs_running" : 2910,
                        "microsecs_running" : NumberLong("2910134851"),
                        "op" : "none",
                        "ns" : "local.oplog.$main",
                        "query" : {

                        },
                        "numYields" : 0,
                        "locks" : {

                        },
                        "waitingForLock" : false,
                        "lockStats" : {
                                "Global" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(1),
                                                "w" : NumberLong(1)
                                        }
                                },
                                "Database" : {
                                        "acquireCount" : {
                                                "w" : NumberLong(1)
                                        }
                                },
                                "Collection" : {
                                        "acquireCount" : {
                                                "w" : NumberLong(1)
                                        }
                                }
                        }
                },
                {
                        "desc" : "replslave",
                        "threadId" : "140688683882240",
                        "active" : true,
                        "opid" : 6,
                        "secs_running" : 2910,
                        "microsecs_running" : NumberLong("2910094579"),
                        "op" : "none",
                        "ns" : "local.me",
                        "query" : {

                        },
                        "numYields" : 0,
                        "locks" : {
                                "Global" : "W"
                        },
                        "waitingForLock" : true,
                        "lockStats" : {
                                "Global" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(18788),
                                                "W" : NumberLong(9344)
                                        },
                                        "acquireWaitCount" : {
                                                "W" : NumberLong(3)
                                        },
                                        "timeAcquiringMicros" : {
                                                "W" : NumberLong(92534923)
                                        }
                                },
                                "Database" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(4722)
                                        }
                                },
                                "Collection" : {
                                        "acquireCount" : {
                                                "r" : NumberLong(4722)
                                        }
                                }
                        }
                }
        ],
        "fsyncLock" : true,
        "info" : "use db.fsyncUnlock() to terminate the fsync write/snapshot lock",
        "ok" : 1
}

　　

解锁

> db.fsyncUnlock()db.fsyncUnlock()
{ "info" : "fsyncUnlock completed", "lockCount" : NumberLong(0), "ok" : 1 }
>

　　

从库上操作

这个命令用于，先同步完数据，再锁住写操作，只能在从库上操作，在主库上会提示如下：
> db.runCommand({fsync:1,lock:1})
{
        "ok" : 0,
        "errmsg" : "fsync may only be run against the admin database.",
        "code" : 13,
        "codeName" : "Unauthorized"
}
>