A low latency garbage collector capable of handling heaps ranging from a few gigabytes to multi terabytes in size, with GC pause times not exceeding 10ms.
Questions tagged [zgc]
30 questions
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How stable is Z Garbage Collector introduced with Java11?
I am using Java 11 and the new Z garbage collector(ZGC) seems really promising.
Docs say that it uses some low-latency garbage collection mechanism such that GC pause times never exceeds 10 ms, handles large heaps extremely well and allows to…
Amit kumar
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Undestanding a detail about the colour bits in the ZGC algorithm
I'm trying to understand how ZGC works in detail. Let's consider a simple Java example:
var v = new Object[]{ new Object() };
Let's call
a: the array object
o: the object referenced by v[0]
r: the reference to a
s: the reference to o
The…
user120513
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ZGC used a lot of cache after startup
ZGC used alot of cache after startup even there is no request
OS: docker
jdk: openjdk version "17.0.8" 2023-07-18
This is the start command for my container
CMD ["java","-Xms1g","-Xmx1g","-XX:+UseZGC","-jar","/root/access-1.0.0.jar"]
The…
liber
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What do GC Pause and GC Cycles mean in JDK Misson Control using ZGC and ShenandoahGC?
When using Serial, Parallel or G1 GCs I can directly see their Collection Counts and accumulated times. However when using ZGC and ShenandoahGC it shows two different Counts and Times for each - for Pause and for Cycles.
Which one of these is the…
TKret96
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ZGC and Xmx and vm.max_map_count
We have a java 17 application which run with theses options:
-Xmx100g
-XX:+UseZGC
When running it, these gc warnings appear:
[warning][gc]
***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****
The system limit on number of memory mappings…
Arya
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Java 17 ZGC - "SoftMaxHeapSize" related question
as far as I understood SoftMaxHeapSize in Java (in this case Java 17 with ZGC), it makes sure that the memory usage stays within the set SoftMaxHeapSize limit as long as possible and only uses more memory if there is no other way, until the limit…
sebkoe
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What does the mmu line mean in zgc log?
In a typical detailed zgc log, what's the meaning of these numbers in this mmu line?
[gc,mmu ] GC(18939) MMU: 2ms/0.0%, 5ms/0.0%, 10ms/0.0%, 20ms/0.0%, 50ms/36.2%, 100ms/68.0%
I've searched and read several pages but still got no expression on…
Garrus
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How can ZGC avoid to scan the large local cache to reduce the concurrent mark time of GC cycle?
There is a 3GB local cache in my service（the total mem of my server is 16GB）, by using ZGC in JDK11, I found out that the concurrent mark time is too long in each cycle(almost 5 seconds if there are 2 concurrent threads).
So I'm wondering if there…
Xi Yang
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ZGC used memory spikes upto to max
Scratching my head to figure out if those spikes is something I should concern about or it's sort of normal behavior and it's more about how my app works? I tried to check if my service caught OOM but looks like nope. Here is the JVM arguments I use…
slesh
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ZGC bad cycle and don't stop with all CPU in jdk17
I'm using jdk17 to run some app, at first it's all right, after about 12 hours correct working, suddenly the service don't response and the gc log show like below
Out of address space
Force to lower max java heap size from 50G(100%) to…
0
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1 answer
Is UseGCOverheadLimit supported by ZGC?
we are currently using G1GC which does not honour/support UseGCOverheadLimit, so our app is sometimes completely stuck in GC-thrashing and the jvm never aborts/crashes.
Just checking which options we do have, according to this overview the latest GC…
hotzen
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JDK16 ZGC problems when started
Recently，I try to do some test on JDK16's new GC ,namely ZGC ,but when I plan to reset the value of GC paramter -XX:+UseLargePages and the JVM start failed .In the log ,it says ,
[2021-04-15T20:11:10.094+0800] Heap Backing…
qi hu
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1 answer
how to count zgc result(gc time and heap usage)
the result of jstat -gcutil is suitable for generational garbage collection, but how can I count the zgc result?
nzomkxia
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Is remap flag set by gc in ZGC?
A garbage collection cycle of ZGC has in essential two phases: marking and relocating. During the marking phase in all references to a live object one of the flags marked0 or marked1 is set (the flags are usesd alternatingly by the garbage…
user120513
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1 answer
[ZGC]Why the memory used is much larger than the dump file?
Here is some information:
Linux version 3.18.6-2.el7.centos.x86_64、openjdk-11.0.2
using ZGC and -Xms16384M -Xmx16384M
top command shows : 17.013t VIRT, 0.016t RES, 0.015t SHR, 35.2 %CPU, 13.0%MEM
heap dump size is 83M(using jcmd command)
VisualVM…
huaiyu
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