executorservice - How is an executor terminated in my Java program? -
this question related previous question : why speed of java process within multiple loops slows downwards goes?
in order find problem of question, looked closely @ code , found executors in app not terminated, since i'm in process of learning how utilize executors, copied online sample codes , used them in app, , i'm not sure if i'm using them correctly.
what's difference between next 2 approaches of using executors ?
[1]
executor executor=executors.newfixedthreadpool(30); countdownlatch donesignal=new countdownlatch(280); (int n=0;n<280;n++) { ... executor.execute(new samplecountrunner(donesignal,...)); } seek { donesignal.await(); } grab (exception e) { e.printstacktrace(); } [2]
executorservice executor=executors.newfixedthreadpool(30); (int i=0;i<60;i++) { ... executor.execute(new xyzrunner(...)); } executor.shutdown(); while (!executor.isterminated()) { } it seems me after 1st 1 done, executor still has active pool of threads running , waiting more tasks, consume cpu time , memory.
the 2nd 1 terminate active threads in pool after shutdown() method run, , active threads won't take more cpu time or memory after point.
so questions :
[1] right ?
[2] how terminate pool of threads in 1st case ? there no "executor.shutdown()" executor
edit :
problem solved, changed executor in [1] executorservice, , added :
executor.shutdown(); while (!executor.isterminated()) { } now when programme ends, won't have lot of threads active more.
it seems me after 1st 1 done, executor still has active pool of threads running , waiting more tasks, consume cpu time , memory.
not exactly. in first approach , after tasks done ( signalled latch ) , executor not shutdown - threads in executor not consume cpu ( consume minimum memory needed thier structures yes ).
in approach - explicitly in command of knowing when , how tasks completed. can know if tasks have succeeded or failed , , can decide resubmit tasks if needed.
the 2nd 1 terminate active threads in pool after shutdown() method run, , active threads won't take more cpu time or memory after point.
again ,not .in approach , executorservice not shutdown after phone call shutdown(). waits submitted tasks finish , here not straight know if these tasks completed or failed ( throwing exception ).
and until submitted tasks completed - isshutdown() tight loop ( spike cpu near 100% ) .
java executorservice executor
