Race condition EBean 14 about ebean

[tbee]

Alternatively one can add to e.g. LoadManyRequest.createQuery code to use the existing transaction:

    if (this.transaction() != null) {
      query.usingTransaction(transaction);
    }

Or in DefaultBeanLoader

  void loadMany(LoadManyRequest loadRequest) {
    SpiQuery<?> query = loadRequest.createQuery(server);
    query.usingTransaction(loadRequest.transaction());
    executeQuery(loadRequest, query);
    loadRequest.postLoad();
  }

This feels like a better approach. Where the last one seems like it could be the fix, because it mirrors loadBean in the same class.

[tbee]

It appears the second connection is for a ImplicitReadOnlyTransaction which has its own connection.

First connection is used:

logSql:405, CQueryEngine (io.ebeaninternal.server.query)
findMany:348, CQueryEngine (io.ebeaninternal.server.query)
findMany:126, DefaultOrmQueryEngine (io.ebeaninternal.server.query)
findList:403, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1430, DefaultServer (io.ebeaninternal.server.core)
findOne:1060, DefaultServer (io.ebeaninternal.server.core)
findOne:1569, DefaultOrmQuery (io.ebeaninternal.server.querydefn)
findOne:429, DefaultExpressionList (io.ebeaninternal.server.expression)
byUUID:54, UserFinder (com.nedap.healthcare.administration.authorization.finder)
...

Second connection is used:

sql:40, DTxnLogger (io.ebeaninternal.server.logger)
logSql:443, ImplicitReadOnlyTransaction (io.ebeaninternal.server.transaction)
logSql:405, CQueryEngine (io.ebeaninternal.server.query)
findMany:348, CQueryEngine (io.ebeaninternal.server.query)
findMany:126, DefaultOrmQueryEngine (io.ebeaninternal.server.query)
findList:403, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1430, DefaultServer (io.ebeaninternal.server.core)
findList:1409, DefaultServer (io.ebeaninternal.server.core)
executeQuery:149, DefaultBeanLoader (io.ebeaninternal.server.core)
loadMany:37, DefaultBeanLoader (io.ebeaninternal.server.core)
loadMany:462, DefaultServer (io.ebeaninternal.server.core)
loadSecondaryQuery:98, DLoadManyContext (io.ebeaninternal.server.loadcontext)
executeSecondaryQueries:192, DLoadContext (io.ebeaninternal.server.loadcontext)
executeSecondaryQueries:121, OrmQueryRequest (io.ebeaninternal.server.core)
findMany:357, CQueryEngine (io.ebeaninternal.server.query)
findMany:126, DefaultOrmQueryEngine (io.ebeaninternal.server.query)
findList:403, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1430, DefaultServer (io.ebeaninternal.server.core)
findOne:1060, DefaultServer (io.ebeaninternal.server.core)
findOne:1569, DefaultOrmQuery (io.ebeaninternal.server.querydefn)
findOne:429, DefaultExpressionList (io.ebeaninternal.server.expression)
byUUID:54, UserFinder (com.nedap.healthcare.administration.authorization.finder)
...

[tbee]

It seems this setup maybe intended for use with a ReadonlyDatasource. But setting that up shows that the two nested getConnections both claim from the readonly datasource, thus does not solve the problem. (The first working get/return claims from the normal pool.)

[tbee]

Below are the two stacktraces of the two claims for a connection without returning in between.

getConnection:276, SemaphoreConcurrentLinkedDequeManagedConnectionPool (org.jboss.jca.core.connectionmanager.pool.mcp)
getSimpleConnection:640, AbstractPool (org.jboss.jca.core.connectionmanager.pool)
getConnection:605, AbstractPool (org.jboss.jca.core.connectionmanager.pool)
getManagedConnection:624, AbstractConnectionManager (org.jboss.jca.core.connectionmanager)
getManagedConnection:440, TxConnectionManagerImpl (org.jboss.jca.core.connectionmanager.tx)
allocateConnection:789, AbstractConnectionManager (org.jboss.jca.core.connectionmanager)
getConnection:151, WrapperDataSource (org.jboss.jca.adapters.jdbc)
getConnection:64, WildFlyDataSource (org.jboss.as.connector.subsystems.datasources)
createReadOnlyTransaction:32, TransactionFactoryBasicWithRead (io.ebeaninternal.server.transaction)
createReadOnlyTransaction:294, TransactionManager (io.ebeaninternal.server.transaction)
createReadOnlyTransaction:2153, DefaultServer (io.ebeaninternal.server.core)
initTransIfRequired:219, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1429, DefaultServer (io.ebeaninternal.server.core)
findOne:1060, DefaultServer (io.ebeaninternal.server.core)
findOne:1569, DefaultOrmQuery (io.ebeaninternal.server.querydefn)
findOne:429, DefaultExpressionList (io.ebeaninternal.server.expression)
byUUID:54, UserFinder (com.nedap.healthcare.administration.authorization.finder)
byUuid:607, UserResource (com.nedap.healthcare.administration.rest)
userByUuid:155, UserResource (com.nedap.healthcare.administration.rest)
...

getConnection:276, SemaphoreConcurrentLinkedDequeManagedConnectionPool (org.jboss.jca.core.connectionmanager.pool.mcp)
getSimpleConnection:640, AbstractPool (org.jboss.jca.core.connectionmanager.pool)
getConnection:605, AbstractPool (org.jboss.jca.core.connectionmanager.pool)
getManagedConnection:624, AbstractConnectionManager (org.jboss.jca.core.connectionmanager)
getManagedConnection:440, TxConnectionManagerImpl (org.jboss.jca.core.connectionmanager.tx)
allocateConnection:789, AbstractConnectionManager (org.jboss.jca.core.connectionmanager)
getConnection:151, WrapperDataSource (org.jboss.jca.adapters.jdbc)
getConnection:64, WildFlyDataSource (org.jboss.as.connector.subsystems.datasources)
createReadOnlyTransaction:32, TransactionFactoryBasicWithRead (io.ebeaninternal.server.transaction)
createReadOnlyTransaction:294, TransactionManager (io.ebeaninternal.server.transaction)
createReadOnlyTransaction:2153, DefaultServer (io.ebeaninternal.server.core)
initTransIfRequired:219, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1429, DefaultServer (io.ebeaninternal.server.core)
findList:1409, DefaultServer (io.ebeaninternal.server.core)
executeQuery:149, DefaultBeanLoader (io.ebeaninternal.server.core)
loadMany:37, DefaultBeanLoader (io.ebeaninternal.server.core)
loadMany:462, DefaultServer (io.ebeaninternal.server.core)
loadSecondaryQuery:98, DLoadManyContext (io.ebeaninternal.server.loadcontext)
executeSecondaryQueries:192, DLoadContext (io.ebeaninternal.server.loadcontext)
executeSecondaryQueries:121, OrmQueryRequest (io.ebeaninternal.server.core)
findMany:357, CQueryEngine (io.ebeaninternal.server.query)
findMany:126, DefaultOrmQueryEngine (io.ebeaninternal.server.query)
findList:403, OrmQueryRequest (io.ebeaninternal.server.core)
findList:1430, DefaultServer (io.ebeaninternal.server.core)
findOne:1060, DefaultServer (io.ebeaninternal.server.core)
findOne:1569, DefaultOrmQuery (io.ebeaninternal.server.querydefn)
findOne:429, DefaultExpressionList (io.ebeaninternal.server.expression)
byUUID:54, UserFinder (com.nedap.healthcare.administration.authorization.finder)
byUuid:607, UserResource (com.nedap.healthcare.administration.rest)
userByUuid:155, UserResource (com.nedap.healthcare.administration.rest)
...

The second stacktrace has two different requests objects in DefaultServer line 1429. They are constructed just above in line 1414. It would make sense that the second request reuses the readonly connection obtained by the first request.

Under EBean 12 this nesting indeed does not happen. And if an explicit JTA transaction is started, both request use that connection.

[tbee]

I was able to patch the behaviour by introducing a ThreadLocal variable in OrmQueryRequest.initTransIfRequired and solely for createReadOnlyTransaction store the first transaction within a thread, and return that on subsequent calls. Does not seem like the correct way to fix it, but it appears to work.

[tbee]

Any idea when a bugfix release will come out?

[rbygrave]

Should be on the way to central, so should be available in about 20 minutes.