I looked into rolling my own connection manager, but (a) I bumped into a whole bunch of deprecated classes, and then (b) when trying to work it in with the latest code on trunk, I bumped into a stack full of classes that rely on synchronization and locking.
I shelved the project for now, but at some point I'm going to need to tackle this, since it's definitely a bottleneck... On Sun, Jan 22, 2012 at 5:55 AM, Dvora <barak.ya...@gmail.com> wrote: > > Hi, > > I'm running into similar problems, have you find a way to solve/workaround > the issue? > > Thanks. > > > dcheckoway wrote: > > > > Hello, > > > > I have an app that needs to make concurrent HTTP requests to a web > service > > using persistent (keepalive) connections. I'm using > > ThreadSafeClientConnManager. I ran into a performance bottleneck, and I > > believe I've pinpointed the issue... > > > > Affects Version(s): HttpCore 4.1.3, HttpClient 4.1.2 > > > > I construct my connection manager and client like this: > > > > connMgr = new > > ThreadSafeClientConnManager(SchemeRegistryFactory.createDefault(), -1, > > TimeUnit.MILLISECONDS); > > connMgr.setMaxTotal(400); > > connMgr.setDefaultMaxPerRoute(400); > > > > httpClient = new DefaultHttpClient(connMgr); > > > > Note that this app only talks to a single URI on a single server -- thus > > defaultMaxPerRoute == maxTotal, which I think is correct...please let me > > know if that's bad! > > > > Anyway, my app has a pool of 400 threads and generally performs quite > > well. But when all 400 threads need a connection concurrently, > > performance > > suffers. I've narrowed it down to contention caused by blocking calls in > > the connection manager. For example...a thread dump shows... > > > > About half my threads are "stuck" (well, not stuck, but slow & waiting) > > here: > > > > "catalina-exec-347" daemon prio=10 tid=0x00007f3a54065000 nid=0x6b73 > > waiting on condition [0x00007f3a29b9a000] > > java.lang.Thread.State: WAITING (parking) > > at sun.misc.Unsafe.park(Native Method) > > - parking to wait for <0x00000006147c8318> (a > > java.util.concurrent.locks.ReentrantLock$NonfairSync) > > at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:842) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1178) > > at > > > java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:186) > > at > > java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262) > > at > > > org.apache.http.impl.conn.tsccm.ConnPoolByRoute.freeEntry(ConnPoolByRoute.java:438) > > at > > > org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager.releaseConnection(ThreadSafeClientConnManager.java:276) > > - locked <0x000000062048ebc8> (a > > org.apache.http.impl.conn.tsccm.BasicPooledConnAdapter) > > at > > > org.apache.http.impl.conn.AbstractClientConnAdapter.releaseConnection(AbstractClientConnAdapter.java:308) > > - locked <0x000000062048ebc8> (a > > org.apache.http.impl.conn.tsccm.BasicPooledConnAdapter) > > at > > > org.apache.http.conn.BasicManagedEntity.releaseManagedConnection(BasicManagedEntity.java:181) > > at > > > org.apache.http.conn.BasicManagedEntity.eofDetected(BasicManagedEntity.java:142) > > at > > > org.apache.http.conn.EofSensorInputStream.checkEOF(EofSensorInputStream.java:211) > > at > > > org.apache.http.conn.EofSensorInputStream.read(EofSensorInputStream.java:139) > > ... > > > > While the other half are "stuck" here: > > > > "catalina-exec-346" daemon prio=10 tid=0x00007f3a4c05d000 nid=0x6b72 > > waiting on condition [0x00007f3a29c9b000] > > java.lang.Thread.State: WAITING (parking) > > at sun.misc.Unsafe.park(Native Method) > > - parking to wait for <0x00000006147c8318> (a > > java.util.concurrent.locks.ReentrantLock$NonfairSync) > > at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:842) > > at > > > java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1178) > > at > > > java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:186) > > at > > java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262) > > at > > > org.apache.http.impl.conn.tsccm.ConnPoolByRoute.getEntryBlocking(ConnPoolByRoute.java:337) > > at > > > org.apache.http.impl.conn.tsccm.ConnPoolByRoute$1.getPoolEntry(ConnPoolByRoute.java:300) > > at > > > org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager$1.getConnection(ThreadSafeClientConnManager.java:224) > > at > > > org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:401) > > at > > > org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:820) > > at > > > org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:941) > > ... > > > > It's not a deadlock per se. It's just a bottleneck, and it is causing > > very > > high latency in my app. Below a certain threshold, i.e. when not all 400 > > threads need a connection concurrently, things are fine. But when all > 400 > > need a connection at once, that's when it gets painful. > > > > I'm wondering if it might be feasible to switch to using non-blocking > > calls > > for this, i.e. with ConcurrentHashMap and/or ConcurrentLinkedQueue, or > > something of that nature? I haven't dived into the source code yet, so > > don't slap me too hard if that suggestion was way out of line. :-) > > > > Do you have any suggestions, in terms of ways I might be able to work > > around this bottleneck otherwise? > > > > Thanks! > > > > Dan Checkoway > > > > > > -- > View this message in context: > http://old.nabble.com/Possibility-of-using-non-blocking-calls-for-connection-pools--tp33093916p33182743.html > Sent from the HttpClient-User mailing list archive at Nabble.com. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: httpclient-users-unsubscr...@hc.apache.org > For additional commands, e-mail: httpclient-users-h...@hc.apache.org > >
