737a20b8fa
In general, the current distributed lock is susceptible to time skew in config servers and mongos clients. This update uses an algorithm that checks for time skew, as well as providing some more robust tests to make sure a distributed lock cannot be forced prematurely. Some documentation on the website, currently hidden from non-10gen, gives more info.
70 lines
2.0 KiB
JavaScript
70 lines
2.0 KiB
JavaScript
// Test the (legacy) distributed lock with significant time skewing.
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// Negative test does not always pass, so turned off, but useful to have around.
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test = new SyncCCTest( "sync5-", { logpath : "/dev/null" } )
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var commandConn = startMongodTest( 30000 + 4, "syncCommander", false, { logpath : "/dev/null" } )
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// { logpath : "/data/db/syncCommander/mongod.log" } );
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for ( var i = 0; i < 10; i++ ) {
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command = { _testDistLockWithSkew : 1 }
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command["lockName"] = "TimeSkewTest_lock_" + i;
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command["host"] = test.url
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command["seed"] = i
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command["numThreads"] = ( i % 50 ) + 1
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command["wait"] = 1000
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// Use the legacy logic with 15 mins per lock.
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command["takeoverMins"] = 15
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// Amount of time to hold the lock
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command["threadWait"] = ( ( i + 1 ) * 10 ) % 200
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// Amount of total clock skew possible between locking threads (processes)
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// Must be much less than the takeover minutes
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command["skewRange"] = ( command["takeoverMins"] / 2 ) * 60 * 1000
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result = commandConn.getDB( "admin" ).runCommand( command )
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printjson( result )
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printjson( command )
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assert( result.ok, "Skewed threads did not increment correctly." );
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}
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if ( false ) {
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// Test that the distributed lock fails with more skew.
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var badTakeover = false;
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for ( var i = 0; i < 10 && !badTakeover; i++ ) {
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command = { _testDistLockWithSkew : 1 }
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command["host"] = test.url
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command["seed"] = i
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command["numThreads"] = ( i % 50 ) + 1
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command["wait"] = 1000
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// Use the legacy logic with 15 mins per lock.
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command["takeoverMins"] = 15
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// Amount of time to hold the lock
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command["threadWait"] = ( ( i + 1 ) * 10 ) % 200
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// Amount of total clock skew possible between locking threads
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// (processes)
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// Must be much less than the takeover minutes
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command["skewRange"] = ( command["takeoverMins"] * 2 ) * 60 * 1000
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command["localTimeout"] = true
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result = commandConn.getDB( "admin" ).runCommand( command )
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printjson( result )
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printjson( command )
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badTakeover = !result.ok;
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}
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assert( badTakeover, "Skewed threads did not interfere with one another." );
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}
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test.stop();
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