java - Jersey 2.x leaking memory (Finalizer) with simple POST call (Multithreaded) -


the following simple jersey call leaking objects finalizer queue: 

public boolean startexperiment(experiment experiment) {         final client client = clientbuilder.newclient();         response response = null;         rundescriptor rundescr = experiment.getrundescriptor();         try {             final webtarget webtarget = client.target(experimentcontroller.getinstance().getrunnerurl()).path("runs").path("startnewasyncrun");             response = webtarget.request().post(entity.entity(rundescr, mediatype.application_json));             if (response != null && response.getstatusinfo().getstatuscode() != status.created.getstatuscode()) {                 system.out.println("error, run not created! response info: " + response.getstatusinfo());                 return false;             } else {                 return true;             }         } {             if(response != null) {                 response.close();             }             client.close();         }      }

jersey versions tested: 2.18, 2.20, 2.22.2, 2.23.1. code run multiple threads (each thread running once every minute, example). closing response , client should not necessary, added jsut in case test if help. eclipse mat shows finalizer queue growing objects of type:

  • sun.security.ssl.sslsocketimplementation
  • java.io.fileinputstream
  • sun.net.www.protocol.https.delegatehttpsurlconnection
  • org.glassfish.jersey.client.clientruntime
  • zipfileinflaterinputstream

any or thoughts on matter appreciated!

while not familiar eclipse mat , showing you, proper behavior objects go through finalizer queue.

under normal circumstances, object overrides finalize method queued finalization (which consists of calling finalize method). general idea when garbage collector identifies object unreachable, looks see if finalize method overridden , has not yet been called. if finalize defined , has not yet been called, object queued finalization, otherwise memory collected.

the finalizer appears implemented queue serviced single thread. thread processes each object in queue calling finalize. after call finalize completes, object removed queue.

subsequently, when garbage collector again determines object unreachable, find finalize overridden, has been called. member collected.

note using feature delays collection of garbage. , while convenient way clean object, jvm not guarantee when or if finalize method called.

one related risk "finalizer starvation." mention "growing" perhaps issue facing. if create enough garbage requires finalization , if finalization takes long, can run out of memory because single finalizer queue cannot keep up. there number of ways deal situation:

  • make execution of finalize complete (infinite loops bad) , quickly.
  • avoid synchronization in finalize.
  • make finalizer thread have highest execution priority. can accomplished creating garbage instance changes thread priority in finalizer - create 1 of these during app initialization.

if seeing starvation, use thread dump see finalizer thread working on.


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