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Posted to dev@tinkerpop.apache.org by "Kieran Sherlock (JIRA)" <ji...@apache.org> on 2015/08/27 19:24:45 UTC

[jira] [Created] (TINKERPOP3-814) ConnectionPool can fill with dead Connections

Kieran Sherlock created TINKERPOP3-814:
------------------------------------------

             Summary: ConnectionPool can fill with dead Connections
                 Key: TINKERPOP3-814
                 URL: https://issues.apache.org/jira/browse/TINKERPOP3-814
             Project: TinkerPop 3
          Issue Type: Bug
          Components: driver
    Affects Versions: 3.0.0-incubating
         Environment: "Cluster" of a single gremlin-server/Titan node.  Single client.  minConnectionPoolSize = 2; maxConnectionPoolSize = 10.
            Reporter: Kieran Sherlock
            Assignee: stephen mallette


Client gets a GryoMessageSerializerV1d0 decoding error on a couple of requests (different unfiled issue).   ConnectionPool gets into the situation where there are 2 dead connections being maintained in the pool, but no new connections are being issued.

A sample of the log output...

{noformat}
2015-08-27 09:57:18,122 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Borrowing connection from pool on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin} - timeout in 3000 MILLISECONDS
2015-08-27 09:57:18,122 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Return least used Connection{host=Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}, isDead=false, borrowed=1, pending=0} on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}
2015-08-27 09:57:18,122 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.Client  - Submitted RequestMessage{, requestId=0349c1ce-19dc-4d54-9ca9-30965c9314ae, op='eval', processor='', args={<redacted>}} to - Connection{host=Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}}
2015-08-27 09:57:18,125 [gremlin-driver-worker-6] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Attempting to return Connection{host=Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}} on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}
2015-08-27 09:57:18,126 [gremlin-driver-worker-6] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - On Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin} pool size of 3 > minPoolSize 2 and borrowed of 0 <= minSimultaneousUsagePerConnection 8 so destroy Connection{host=Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}, isDead=false, borrowed=0, pending=0}
2015-08-27 09:57:18,126 [gremlin-driver-worker-6] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Connection{host=Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}, isDead=false, borrowed=0, pending=0} destroyed
2015-08-27 09:57:18,126 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Borrowing connection from pool on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin} - timeout in 3000 MILLISECONDS
2015-08-27 09:57:18,126 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Pool was initialized but a connection could not be selected earlier - waiting for connection on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}
2015-08-27 09:57:18,126 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Wait 3000 MILLISECONDS for an available connection on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin} with Thread[Grizzly-worker(15),5,main]
2015-08-27 09:57:21,127 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Continue to wait for connection on -1 if {} > 0
2015-08-27 09:57:21,127 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Timed-out waiting for connection on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin} - possibly unavailable
2015-08-27 09:57:21,127 [gremlin-driver-worker-3] DEBUG org.apache.tinkerpop.gremlin.driver.Host  - Trying to reconnect to dead host at Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}
2015-08-27 09:57:21,128 [Grizzly-worker(15)] DEBUG org.apache.tinkerpop.gremlin.driver.Client  - Submitted RequestMessage{, requestId=67761973-7ae7-4a6a-8e62-443fdb55142d, op='eval', processor='', args=<redacted>} to - connection not initialized
2015-08-27 09:57:21,128 [gremlin-driver-worker-3] DEBUG org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Trying to re-establish connection on Host{address=localhost/127.0.0.1:18182, hostUri=ws://localhost:18182/gremlin}
2015-08-27 09:57:21,128 [Grizzly-worker(15)] ERROR EdnaMetaDataServiceGremlinImpl  - Failed man lookupMerchantAccountName
java.lang.RuntimeException: java.lang.RuntimeException: java.util.concurrent.TimeoutException
{noformat}

This behavior continues with each subsequent request.  The gremlin-server is available at all times.

As a workaround I have applied the following patch, but I am pretty sure it is not the correct solution

{noformat}
diff --git a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
index 30cd71f..cb8ebfa 100644
--- a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
+++ b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/ConnectionPool.java
@@ -352,7 +352,7 @@ final class ConnectionPool {
             }

             remaining = to - TimeUtil.timeSince(start, unit);
-            logger.debug("Continue to wait for connection on {} if {} > 0", remaining);
+            logger.debug("Continue to wait for connection on {} if {} > 0", host, remaining);
         } while (remaining > 0);

         logger.debug("Timed-out waiting for connection on {} - possibly unavailable", host);
@@ -371,13 +371,16 @@ final class ConnectionPool {

         // let the load-balancer know that the host is acting poorly
         this.cluster.loadBalancingStrategy().onUnavailable(host);
-
     }

     private boolean tryReconnect(final Host h) {
         logger.debug("Trying to re-establish connection on {}", host);

         try {
+            // remove dead connections
+            for (Connection c : connections)
+                if (c.isDead())
+                    definitelyDestroyConnection(c);
             connections.add(new Connection(host.getHostUri(), this, cluster, settings().maxInProcessPerConnection));
             this.open.set(connections.size());
{noformat}




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