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Questions tagged [g1gc]

G1 or Garbage First is a generational partially collecting concurrent and parallel garbage collection algorithm. It is targeted for multi-processor machines with large memories and can meet soft realtime requirements with garbage collection (GC) pause time goals. An implementation of the G1 currently ships with the new Java 7 VMS - officially supported from JDK7 update 4.

G1 or "Garbage First" is a generational partially collecting concurrent and parallel garbage collection algorithm. It is targeted for multi-processor machines with large memories and can meet soft realtime requirements with garbage collection (GC) pause time goals.

An implementation of the G1 currently ships with the Java Hotspot 7 VM - officially supported from JDK7 update 4.

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G1 GC -- extremely long termination time

A seemingly straightforward question: why does G1 GC spend so much time in the 'termination' phase? A non-full GC takes ~2 seconds, and from that, 1.5 sec is the termination (work stealing) phase. Context: - our app has apprx. 10MB/sec allocation…
Mate Varga
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Java G1 GC tuning issue: old regions not collected

I am currently trying to tune Apache NiFi to get it work with a high throughput flow, but I cannot avoid Full GCs. When the flow is started, really quick young GCs occur, but they are not able to cope with the allocation demand until eventually the…
riccamini
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Why G1 gives better pause time but lower throughput?

Why G1 gives less pause time but lower throughput(lower throughput means GC will be running more total time in seconds) Per mine understanding as memory is divided into smaller parts, now full has to be run on smaller portion than complete heap . In…
emilly
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When will the Java VM support the Garbage First (G1) Collector for Linux ARM?

I am currently developing project which involves running a system on ARM, using java as the main execution language. Unfortunately Java 7 VM does not support the G1 gc for ARM boards, but I have not found anything about G1 support on ARM in Java…
Mr. Andrey
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Why does G1 cost so much time for object copy?

The following is my gc log: 2016-08-16T01:45:35.968+0000: 62265.934: [GC pause (G1 Evacuation Pause) (young) Desired survivor size 473956352 bytes, new threshold 15 (max 15) - age 1: 12641224 bytes, 12641224 total - age 2: 3092400 bytes,…
bychjzh
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G1 long young GC time when initiating concurrent marking cycle

JDK version: java version "1.7.0_91" OpenJDK Runtime Environment (IcedTea 2.6.3) (7u91-2.6.3-0ubuntu0.14.04.1) OpenJDK 64-Bit Server VM (build 24.91-b01, mixed mode) GC/Mem parameters: -Xms24g -Xmx24g -Xss256k -Djava.awt.headless=true…
Rural Hunter
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Followup: G1 Collector not doing full GC

This is followup question to G1 Collector not doing full GC Removed -XX:MaxGCPauseMillis=100 -XX:InitiatingHeapOccupancyPercent=80 Default for IHOP is 45% S0C S1C S0U S1U EC EU OC OU PC PU YGC YGCT FGC FGCT GCT 0 96M 0 96M 3.4G …
Sameer Naik
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How can I configure logstash to parse G1GC loggc files

In our production environment, we have an ELK stack, which we are using for monitoring our own log files. We also have enabled g1-gc…
doc
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JVM Crash with G1 GC Due to Card Table Verification Failure

Recently we started to use OpenJDK JRE instead of Oracle's one. The environment consist of: Tomcat 8.0.29 CentOS 6.7 (2.6.32-279.el6.imp6.numa.x86_64 #1 SMP Wed Mar 30 11:50:42 IDT 2016 x86_64 x86_64 x86_64 GNU/Linux) Java 8 update 71 G1 Garbage…
Maxim Kirilov
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How is number of young regions determined by G1?

can anyone explain me how is the number of young regions determined by G1 collector? The G1 paper states that "we track the fixed and per-regions costs of fully young collections via historic averaging, and use these estimates to determine the…
user2616566
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Using G1GC algorithm in prod do we have any algorithm that it has to do major gc after threshold level

We are using G1GC algoritm in PRODUCTION, using this algorithm in -XX+useg1gc in environment. My question is a few servers in PROD are getting high heap usage about 95%, so do we have any arguments or option or mechanism that major GC should happen…
SATISH RAYAPUDI
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Why switching form serial GC to G1 increase RSS

I have sample app with starting RSS size of 600MB when using serial GC. Once I use G1 RSS memory after bootstrap increases to 800Mb. Does anybody know how I can profile that increase and whenever there any G1 tuning options to improve memory…
Petro Semeniuk
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G1 Garbage collection - repeated full GC - does this represent a heap fragmentation / garbage compaction issue?

I'm Using Java 7 update 76, and G1 garbage collector. Periodically we experience full GCs occurring at small time intervals (every 4 to 5 seconds), it appears memory is being freed, but another full gc occurs very soon afterwards and appears to free…
NottmTony
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Does G1 garbage collector use the same region size for every region?

Oracle's Getting Started with the G1 Garbage Collector tutorial says the following about region sizes with the G1 garbage collector: The heap is one memory area split into many fixed sized regions. [...] Region size is chosen by the JVM at startup.…
levl
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Why the Scan RS spend a long time when I use G1GC

I'm using java1.7.0_67 and run my app with these: -Xms8g -Xmx8g -XX:PermSize=128M -XX:MaxPermSize=128M -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:SoftRefLRUPolicyMSPerMB=0 -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Xloggc:log/gc.log -jar…
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