BaseX parrallel Client - basex

Question

I have client like this :
import org.basex.api.client.ClientSession;
#Slf4j
#Component(value = "baseXAircrewClient")
#DependsOn(value = "baseXAircrewServer")
public class BaseXAircrewClient {
#Value("${basex.server.host}")
private String basexServerHost;
#Value("${basex.server.port}")
private int basexServerPort;
#Value("${basex.admin.password}")
private String basexAdminPassword;
#Getter
private ClientSession session;
#PostConstruct
private void createClient() throws IOException {
log.info("##### Creating BaseX client session {}", basexServerPort);
this.session = new ClientSession(basexServerHost, basexServerPort, UserText.ADMIN, basexAdminPassword);
}
}
It is a singleton injected in a service which run mulitple queries like this :
Query query = client.getSession().query(finalQuery);
return query.execute();
All threads query and share the same session.
With a single thread all is fine but with multiple thread I get some random (and weird) error, like the result of a query to as a result of another.
I feel that I should put a synchronized(){} arround query.execute() or open and close session for each query, or create a pool of session.
But I don't find any documentation how the use the session in parrallel.
Is this implementation fine for multithreading (and my issue is comming from something else) or should I do it differently ?

Answer 1

I ended creating a simple pool by adding removing the client from a ArrayBlockingQueue and it is working nicely :
#PostConstruct
private void createClient() throws IOException {
log.info("##### Creating BaseX client session {}", basexServerPort);
final int poolSize = 5;
this.resources = new ArrayBlockingQueue < ClientSession > (poolSize) {
{
for (int i = 0; i < poolSize; i++) {
add(initClient());
}
}
};
}
private ClientSession initClient() throws IOException {
ClientSession clientSession = new ClientSession(basexServerHost, basexServerPort, UserText.ADMIN, basexAdminPassword);
return clientSession;
}
public Query query(String finalQuery) throws IOException {
ClientSession clientSession = null;
try {
clientSession = resources.take();
Query result = clientSession.query(finalQuery);
return result;
} catch (InterruptedException e) {
log.error("Error during query execution: " + e.getMessage(), e);
} finally {
if (clientSession != null) {
try {
resources.put(clientSession);
} catch (InterruptedException e) {
log.error("Error adding to pool : " + e.getMessage(), e);
}
}
}
return null;
}