Jeff: Thanks for reporting the bug. Patch is available in HBASE-8222. It should go into 0.94.7
If you cannot wait, feel free to apply by yourself. On Fri, Mar 29, 2013 at 12:44 PM, Jeff Whiting <je...@qualtrics.com> wrote: > I am using cdh4.1.3 which roughly maps to 0.92.1 with patches. > > ~Jeff > > > On Fri, Mar 29, 2013 at 1:40 PM, ramkrishna vasudevan < > ramkrishna.s.vasude...@gmail.com> wrote: > > > Nice one.. Good find. > > > > > > On Sat, Mar 30, 2013 at 12:30 AM, Ted Yu <yuzhih...@gmail.com> wrote: > > > > > Can you tell us the version of HBase you are using ? > > > > > > Gary did some cleanup in: > > > > > > r1439723 | garyh | 2013-01-28 16:50:02 -0800 (Mon, 28 Jan 2013) | 1 > line > > > > > > HBASE-7626 Backport client connection cleanup from HBASE-7460 > > > > > > This is the current code in getConnection() in 0.94 branch: > > > ConnectionId remoteId = new ConnectionId(addr, protocol, ticket, > > > rpcTimeout); > > > synchronized (connections) { > > > connection = connections.get(remoteId); > > > if (connection == null) { > > > connection = createConnection(remoteId); > > > connections.put(remoteId, connection); > > > } > > > } > > > connection.addCall(call); > > > > > > > > > On Fri, Mar 29, 2013 at 11:41 AM, Jeff Whiting <je...@qualtrics.com> > > > wrote: > > > > > > > After noticing a lot of threads, I turned on debugging logging for > > hbase > > > > client and saw this many times counting up constantly: > > > > HBaseClient:531 - IPC Client (687163870) connection to > > > > /10.1.37.21:60020from jeff: starting, having connections 1364 > > > > > > > > At that point in my code it was up to 1364 different connections (and > > > > threads). Those connections will eventually drop off after the idle > > time > > > > is reached "conf.getInt("hbase.ipc.client.connection.maxidletime", > > > 10000)". > > > > But during periods of activity the number of threads can get very > high. > > > > > > > > Additionally I was able to confirm the large number of threads by > > doing: > > > > > > > > jstack <pid> | grep IPC > > > > > > > > > > > > So I started digging around in the code... > > > > > > > > In HBaseClient.getConnection it attempts to reuse previous > connections: > > > > > > > > ConnectionId remoteId = new ConnectionId(addr, protocol, ticket, > > > > rpcTimeout); > > > > do { > > > > synchronized (connections) { > > > > connection = connections.get(remoteId); > > > > if (connection == null) { > > > > LOG.error("poolsize: "+getPoolSize(conf)); > > > > connection = new Connection(remoteId); > > > > connections.put(remoteId, connection); > > > > } > > > > } > > > > } while (!connection.addCall(call)); > > > > > > > > > > > > It does this by using the connection id as the key to the pool. All > of > > > this > > > > seems good except ConnectionId never hashes to the same value so it > > > cannot > > > > reuse any connection. > > > > > > > > From my understanding of the code here is why. > > > > > > > > In HBaseClient.ConnectionId > > > > > > > > @Override > > > > public boolean equals(Object obj) { > > > > if (obj instanceof ConnectionId) { > > > > ConnectionId id = (ConnectionId) obj; > > > > return address.equals(id.address) && protocol == id.protocol > && > > > > ((ticket != null && ticket.equals(id.ticket)) || > > > > (ticket == id.ticket)) && rpcTimeout == id.rpcTimeout; > > > > } > > > > return false; > > > > } > > > > > > > > @Override // simply use the default Object#hashcode() ? > > > > public int hashCode() { > > > > return (address.hashCode() + PRIME * ( > > > > PRIME * System.identityHashCode(protocol) ^ > > > > (ticket == null ? 0 : ticket.hashCode()) )) ^ > rpcTimeout; > > > > } > > > > > > > > It uses the protocol and the ticket in the both functions. However > > going > > > > back through all of the layers I think I found the problem. > > > > > > > > Problem: > > > > > > > > HBaseRPC.java: public static VersionedProtocol getProxy(Class<? > > extends > > > > VersionedProtocol> protocol, > > > > long clientVersion, InetSocketAddress addr, Configuration conf, > > > > SocketFactory factory, int rpcTimeout) throws IOException { > > > > return getProxy(protocol, clientVersion, addr, > > > > User.getCurrent(), conf, factory, rpcTimeout); > > > > } > > > > > > > > User.getCurrent() always returns a new User object. That user > instance > > > is > > > > eventually passed down to ConnectionId. However the User object > > doesn't > > > > implement hash() or equals() so one ConnectionId won't ever match > > another > > > > ConnectionId. > > > > > > > > > > > > There are several possible solutions. > > > > 1. implement hashCode and equals for the User. > > > > 2. only create one User object and reuse it. > > > > 3. don't look at ticket in ConnectionId (probably a bad idea) > > > > > > > > > > > > Thoughts? Has anyone else noticed this behavior? Should I open up a > > > jira > > > > issue? > > > > > > > > I originally ran into the problem due to OS X having a limited number > > of > > > > threads per user (and I was not able to increase the limit) and our > > unit > > > > tests making requests quick enough that I ran out of threads. I > tried > > > out > > > > all three solutions and it worked fine for my application. However > I'm > > > not > > > > sure what changing the behavior would do to other's applications > > > especially > > > > those that use SecureHadoop. > > > > > > > > > > > > > > > > Thanks, > > > > ~Jeff > > > > > > > > -- > > > > Jeff Whiting > > > > Qualtrics Senior Software Engineer > > > > je...@qualtrics.com > > > > > > > > > > > > > -- > Jeff Whiting > Qualtrics Senior Software Engineer > je...@qualtrics.com >