Java Garbage Collection Induced Latency affecting Performance -


i'm noticing weird phenomenon in application. store objects in hashmap after submitting them server , remove them when response arrives.

i noticed slow performance after running. upon checking, discovered memory usage stays @ 4gb , drops less 1 gb. suspect cleaning lot of objects that's why performance gets bad.

so question why taking java garbage collect late? is, why wait until heap full , garbage collection? shouldn't collect garbage @ regular intervals.

the objects gets stored in hashmap gets created right @ time, not long lived.

this on linux (rhel), oracle jvm hotspot 7. 64-bit. 4 cores. how app run:

java -jar -xmx4g prog.jar

note: have seen this: tuning garbage collections low latency want understand why gc taking long kick in?

it sounds have 1 of 2 issues going on:

  1. if have semi-long lived objects, moved young generation older (like on hotspot mark-compact generation.) is, they'll stop being reference counted collection , start being retained slower gc.
  2. your young generation heap space small usage pattern forcing objects moved young older generation.

i'd @ tuning young generation larger. see generational garbage collection , @ various types of generations.


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