#82 MEMORY CPU BUG OutOfMemory error

J2SSH (50)

0.2.9 latest code, running cpu at 100%, and out of memory.

3STHSTTYPE 02:03:36:347430000 GMT j9mm.126 - at 326DC760 java/lang/Thread.run()V, jit 31FA6144, pc 31A79B80
3STHSTTYPE 02:03:36:347426000 GMT j9mm.126 - at 37F2EEF8 com/sshtools/j2ssh/transport/TransportProtocolCommon.run()V, jit 320DB310, pc 38807784
3STHSTTYPE 02:03:36:347416000 GMT j9mm.126 - at 37F2F128 com/sshtools/j2ssh/transport/TransportProtocolCommon.startBinaryPacketProtocol()V, jit 31F396B4, pc 319A33F4
3STHSTTYPE 02:03:36:347412000 GMT j9mm.126 - at 37F2F1D8 com/sshtools/j2ssh/transport/TransportProtocolCommon.processMessages()Lcom/sshtools/j2ssh/transport/SshMessage;, jit 31EF9F4C, pc 31921FAC
3STHSTTYPE 02:03:36:347405000 GMT j9mm.126 - at 37F331B8 com/sshtools/j2ssh/transport/TransportProtocolInputStream.readMessage()[B, jit 320DE1DC, pc 3880AE00
3STHSTTYPE 02:03:36:347398000 GMT j9mm.126 - at 3279A7A0 java/io/ByteArrayOutputStream.write([BII)V, jit 31DB7130, pc 3163AA20
3STHSTTYPE 02:03:36:347390000 GMT j9mm.101 - J9AllocateIndexableObject() returning NULL! 1073741840 bytes requested for object of class 326DA4E8 from memory space '' id=00000000
3STHSTTYPE 02:03:36:346716000 GMT j9mm.53 - GlobalGC end: workstackoverflow=0 overflowcount=0 weakrefs=12195 soft=2826 phantom=247 finalizers=491 newspace=60029432/60397568 oldspace=434149576/1006632960 loa=0/0


  • mark

    mark - 2009-09-15
    • priority: 5 --> 7
  • mark

    mark - 2009-09-15

    HERE is the fix in the SshMessageStore.java class.

    This was endlessly looping because the timeout passed was 0, and if an EOF happened when trying to get a message, then it would never be able to get the message, and it looped forever, 100% max the cpu, and then the server dies with out of memory exception.

    This works great!

    * <p>
    * Get a message from the store. This method will block until a message
    * with an id matching the supplied filter arrives, the specified timeout
    * is reached or the message store closes. The message is removed from the
    * store.
    * </p>
    * @param messageIdFilter an array of message ids that are acceptable.
    * @param timeout the maximum number of milliseconds to block before
    * returning.
    * @return the next available message
    * @throws MessageStoreEOFException if the message store is closed
    * @throws MessageNotAvailableException if the message is not available
    * after a timeout
    * @throws InterruptedException if the thread is interrupted
    * @since 0.2.0
    public synchronized SshMessage getMessage(int[] messageIdFilter, int timeout) throws MessageStoreEOFException, MessageNotAvailableException, InterruptedException {

    if ((messages.size() <= 0) && isClosed) {
    throw new MessageStoreEOFException();

    if (messageIdFilter == null) {
    return nextMessage();

    //if timeout less than 0, set to 0.
    if (timeout < 0) {
    timeout = 0;

    SshMessage msg=null;//the message
    int tries=0;//number of tries to get message
    int tryLimit=50;//number MAX to try to get message

    while ((messages.size() > 0) || !isClosed) {
    // lookup the message
    msg = lookupMessage(messageIdFilter, true);

    if (msg != null) {
    return msg;
    } else {
    // If the number of tires exceed the limit, throw the exception, can't wait forever, or enless loop and bring down the application.
    if(tries>tryLimit) {
    throw new MessageNotAvailableException();

    // Now wait
    if (!isClosed) {
    //releases the lock on this method.
    wait((timeout == 0) ? interrupt : timeout);

    //Yes, this is not the best solution, but it will work.
    //if we already tried 25 times, and don't have a message, start sleeping a second the next 25 seconds, to give 25 seconds for a response.


    throw new MessageStoreEOFException();

  • mark

    mark - 2009-09-15

    SSHMessageStore java class with fix

  • Sascha Hunold

    Sascha Hunold - 2013-12-13

    Thanks for pointing this out. Indeed, there could be a problem.
    How about changing
    if (!firstPass && (timeout > 0)) {
    throw new MessageNotAvailableException();
    if (!firstPass) {
    throw new MessageNotAvailableException();
    Would it solve the issue? Comments are welcome.
    I don't want to change the code as I am not sure whether we'll experience side effects or not.


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