In TxDistributionInterceptor.remoteGetAndStoreInL1 locks are acquired. Without a transaction these locks are never released. The cache setup is Dist, Async, L1, 2 Nodes, 1 Owner, Optimistic Locking.

In AbstractTxLockingInterceptor.visitGetKeyValueCommand locks are released explicitly if outside of transactions. I fixed this problem by doing the same in OptimisticLockingInterceptor.visitPutKeyValueCommand. It is very likely that this doesn't fix all problems. For instance OptimisticLockingInterceptor.visitPutMapCommand or PessimisticLockingInterceptor.

Cache Config:
<namedCache name="entity">
<jmxStatistics enabled="true" />

<clustering mode="dist">
<stateTransfer fetchInMemoryState="false" timeout="20000" />
<async />
<l1 enabled="true" />
<hash numOwners="1"/>
</clustering>
<locking isolationLevel="READ_COMMITTED"
lockAcquisitionTimeout="15000" useLockStriping="false" />

<eviction maxEntries="10000" strategy="LRU" />
<expiration maxIdle="100000" wakeUpInterval="5000"/>
<storeAsBinary storeKeysAsBinary="true" storeValuesAsBinary="false" enabled="false" />

<transaction transactionMode="TRANSACTIONAL" autoCommit="false" lockingMode="OPTIMISTIC"/>
</namedCache>

Fixed OptimisticLockingInterceptor.visitPutKeyValueCommand:
@Override
public Object visitPutKeyValueCommand(InvocationContext ctx, PutKeyValueCommand command) throws Throwable {
try

{ if (command.isConditional()) markKeyAsRead(ctx, command); return invokeNextInterceptor(ctx, command); }

catch (Throwable te)

{ throw cleanLocksAndRethrow(ctx, te); }

finally

{ //with putForExternalRead the value might be put into L1 without a transaction //we need to release any locks for these cases if (!ctx.isInTxScope()) lockManager.unlockAll(ctx); }

}