No Wait on Blocks
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## No Wait on Blocks

Normally when a JE transaction is blocked on a lock request, it must wait until the requested lock becomes available before its thread-of-control can proceed. However, it is possible to configure a transaction handle such that it will report a deadlock rather than wait for the block to clear.

You do this on a transaction by transaction basis by specifying `DB_TXN_NOWAIT` to the `DbEnv::txn_begin()` method.

For example:

        DbTxn *txn = NULL;
        try {
            envp->txn_begin(NULL, &txn, DB_TXN_NOWAIT);

            ...
        } catch (DbException &de) {
            // Deadlock detection and exception handling omitted
            // for brevity
            ...

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