Igor Sapego created IGNITE-13997:
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Summary: CPP Thin: Transactions can cause deadlock when client
shared in multiple threads
Key: IGNITE-13997
URL: https://issues.apache.org/jira/browse/IGNITE-13997
Project: Ignite
Issue Type: Bug
Components: thin client
Affects Versions: 2.9.1
Reporter: Igor Sapego
In our tests we have detected a deadlock when following piece of code is
executed for more than one thread on our application:
{code:cpp}
ClientTransactions transactions = client.ClientTransactions();
ClientTransaction tx = transactions.TxStart(PESSIMISTIC, READ_COMMITTED);
// This call should atomically get the current value for "key" and put
"value" instead, locking the "key" cache entry at the same time
auto oldValue = cache.GetAndPut(key, value);
// Only the thread able of locking "key" should reach this code. Others have
to wait for tx.Commit() to complete
cache.Put (key, newValue);
// After this call, other thread waiting in GetAndPut for "key" to be
released should be able of continuing
tx.Commit ();
{code:cpp}
The thread reaching "cache.Put (key, newValue);" call, gets blocked in
there, concretely in the lockGuard object created at the beginning of
DataChannel::InternalSyncMessage function (data_channel.cpp:108). After
debugging, we realized that this lockGuard is owned by a different thread,
which is currently waiting on socket while executing GetAndPut function.
According to this, my guess is that data routing for C++ Thin Clients is not
multithread friendly.
Reported in
http://apache-ignite-users.70518.x6.nabble.com/Multithread-transactions-in-a-C-Thin-Client-td35145.html
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