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Problems locking transactions using Hibernate 4.0

Sometimes I have problems with locking, for example:

java.sql.SQLTransactionRollbackException: A lock could not be obtained within the time requested

I am using Hibernate with the C3p0 pool, and Hibernate is configured for optimistic locking.

I also have code that bypasses Hibernate and talks to the database through the independently configured c3p0 pool. This is because this code existed before I switched to Hibernate and it works fine, so I did not see the need to change it at that time.

Now I am wondering if two independently configured c3p0 pools may be causing problems. If not, how can I track down the cause of these exceptions, I have a union between 20 and 100 connections, and I only have twelve threads at a time, and I think that all my transactions / session are closed when I finish with them.

EDIT: now you have a single pool, but still having a problem, get the following error, but no details regarding the reason for this, one thing I noticed is that it always says Managed thread: 3

Exception with lookup
12:42:36,627  WARN ThreadPoolAsynchronousRunner:608 - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@1ff96a2 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12:42:36,628  WARN ThreadPoolAsynchronousRunner:624 - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@1ff96a2 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@fdfb9a (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@914847 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@205390 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
    Pending Tasks: 
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@4e171b
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@ceeecb
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@19f7cec
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1c299f9
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@10ab38a
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@1916a2f
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1d23fbf
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@573b7c
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1027733
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@dfd9b0
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@4cecbb
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@4a0d0b
        com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@19e809d
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@10de0f8
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@2ce568
Pool thread stack traces:
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,JAIKOZ Thread Group]
        org.apache.derby.impl.jdbc.EmbedStatement.close(Unknown Source)
        com.mchange.v1.db.sql.StatementUtils.attemptClose(StatementUtils.java:41)
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask.run(GooGooStatementCache.java:404)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,JAIKOZ Thread Group]
        org.apache.derby.impl.jdbc.EmbedStatement.close(Unknown Source)
        com.mchange.v1.db.sql.StatementUtils.attemptClose(StatementUtils.java:41)
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask.run(GooGooStatementCache.java:404)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,JAIKOZ Thread Group]
        org.apache.derby.impl.jdbc.EmbedStatement.close(Unknown Source)
        com.mchange.v1.db.sql.StatementUtils.attemptClose(StatementUtils.java:41)
        com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask.run(GooGooStatementCache.java:404)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

Maybe this problem

https://forum.hibernate.org/viewtopic.php?p=2390809

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2 answers

, SQLTransactionRollbackException , c3p0 . , Hibernate.

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Hibernate . SQLite . , . , , - .

SQLite , . , . , stickler, , , - ! , , .

:

    /**
     * Enter read section. Increment the latch so commiting
     * threads know how many reads are left till it appropriate
     * to write/commit.
     *
     * @throws InterruptedException the interrupted exception
     */
    public void enterReadSection() throws InterruptedException {
        if (enableReadLock && (transactionLock.availablePermits()==0)) {
            readLock.lock();
            try {
                log.debug("Waiting on database unlock.");
                readWait.await();
            } finally {
                readLock.unlock();
                log.debug("Database Unlocked.");
            }
        }

        if (enableReadLock) {
            synchronized(this) {
                latch = new CountDownLatch((int)latch.getCount()+1);
            }
        }
    }

    /**
     * Exit read section.
     */
    public void exitReadSection( ) {
        if (enableReadLock)
            latch.countDown();
    }

   /**
     * Trx lock.
     *
     * @throws InterruptedException the interrupted exception
     */
    public void trxLock() throws InterruptedException {
        if (enableTrxLock)
            transactionLock.acquire();
    }

    /**
     * Trx unlock.
     */
    public void trxUnlock() {
        if (enableTrxLock)
            transactionLock.release();
    }

    /**
     * Commit lock.
     *
     * @throws InterruptedException the interrupted exception
     */
    public void commitLock() throws InterruptedException {
        if (enableCommitLock) {
            commitLock.acquire();

            //Wait for reading threads to complete
            latch.await();
        }
    }

    /**
     * Commit unlock.
     *
     * @throws InterruptedException the interrupted exception
     */
    public void commitUnlock() throws InterruptedException {
        if(enableCommitLock) {
            commitLock.release();
            releaseRead();
        }
    }

, - , , . , , / concurrency, Oracle, mysql, postgres ..

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