jvm-hotspot Questions
1
Solved
Is there any way to make the JVM cache the optimized native code it generates to a file, to improve the performance of future runs?
Blakely asked 10/6, 2020 at 13:35
2
I'm using Oracle's Java 1.8.0_231.
What is the effect of setting -XX:ActiveProcessorCount=n? I'm not a C++ guy, but I think I see in the HotSpot source code these two uses:
Influence the number ...
Potation asked 23/1, 2020 at 15:54
1
Solved
I am studying the composition of java object header.
Found some documents and some interesting problems.
Under 64 bit vm, the default object head is as follows (Because UseCompressedOops is on by...
Brasca asked 2/4, 2020 at 6:55
5
Solved
What exactly is HotSpot and how does it relate to JVM and OpenJDK? Is it a library? What exactly does it do?
Also, what is the difference between OpenJDK and HotSpot?
Paintbox asked 15/5, 2013 at 14:48
1
When reading the Mark-Compact chapter on The Garbage Collection Handbook, a sequence of alternatives were presented, but most of them looked old / theoretical (for instance, the 2-finger compaction...
Tainataint asked 26/11, 2019 at 5:57
1
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In JEP193, one of the specific goals of VarHandles is to provide an alternative to of using FieldUpdaters and AtomicIntegers (and avoid some of the overhead associated with them).
AtomicIntegers ...
Mackie asked 14/11, 2019 at 17:59
2
I am going through Hotspot JVM garbage collection, i have a question ,
First article says
The throughput goal is measured in terms of the time spent
collecting garbage and the time spent outs...
Yate asked 4/8, 2015 at 10:35
1
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I am using JNI to allow C code to offload some work best done in Java. In this question I was trying to link the libjvm and libjli libraries for my code to work, but now I'm questioning whether I e...
Murraymurre asked 29/6, 2018 at 13:20
4
Solved
How large, in bytes, is a boxed primitive like java.lang.Integer or java.lang.Character in Java?
An int is 4 bytes, a typical pointer is also 4 byte (if not compressed by the JVM). Is the cost for...
Prosy asked 27/1, 2012 at 17:29
12
I upgraded to the latest Java 7u40 on MacOS X and started getting the following message on the console when launching my application using Eclipse. The app works fine but I would like to find out t...
Clairvoyance asked 13/9, 2013 at 20:19
5
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I've been using Java for a while now, and my typical ritual of setting up a new dev machine requires the norm of downloading and installing the latest JDK from Oracle's site.
This prompted an unu...
Plebeian asked 24/6, 2013 at 22:5
1
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While playing with some jcstress code, I noticed two parameters that are very new to me: StressLCM and StressGCM.
The very first thing to do for me was searching for these in the source code itse...
Chrysalid asked 23/5, 2019 at 10:22
2
Solved
Are OpenJDK VM and Oracle Hotspot VM still two different JVMs?
I can't seem to find any somewhat official documentation on anything about OpenJDK VM. Even in OpenJDK homepage there is an HotSpot G...
Dayfly asked 2/6, 2017 at 18:48
1
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I want to understand how JVM works and I have been reading blog posts and documentation. However, things are quite confusing and frequently outdated. I understand as methods get invoked more and mo...
Tense asked 2/3, 2019 at 13:28
1
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I have the below classes.
I have manually compiled the classes using javac and ran the Driver class.
Later removed the entity.class and MyCustomException.class and ran the app like below.
java...
Lanai asked 21/2, 2019 at 14:10
3
Solved
What is the default value for XX:MaxDirectMemorySize?
Binal asked 22/9, 2010 at 21:29
1
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I got the below assembly list as result for JIT compilation for my java program.
mov 0x14(%rsp),%r10d
inc %r10d
mov 0x1c(%rsp),%r8d
inc %r8d
test %eax,(%r11) ; <--- this instruction
mov (...
Circumspection asked 5/1, 2019 at 18:9
1
Solved
CAUTION: it is not a duplicate, please read topic сarefully
https://stackoverflow.com/users/3448419/apangin quote:
The real question is why the code sometimes works when it should not.
The issu...
Umbrella asked 11/12, 2018 at 12:56
2
Solved
for example, the JDK method java.lang.Integer.numberOfLeadingZeros(int):
public static int numberOfLeadingZeros(int i) {
// HD, Figure 5-6
if (i == 0)
return 32;
int n = 1;
if (i >>>...
Fragonard asked 12/10, 2017 at 12:48
2
Solved
Oracle says that on Windows
-Xsssize The default value depends on virtual memory
How i can find out the value of the thread stack size that java allocate on Windows in a given Oracle JVM 8?
...
Trafficator asked 17/7, 2017 at 9:9
1
Solved
When I tried to debug the openjdk9 by netbeans8.2 in win10, I got the following error:
"\"D:/jdk9/jdk9/build/windows-x86_64-normal-server-fastdebug/jdk/bin/java.exe\":
not in executable format: F...
Flosi asked 6/10, 2018 at 14:15
3
According to this link, there is an option to set MaxRamSize manually to restrict the JVM to not use memory beyond this. But I have not seen any documentation of the same. I've never known this. Is...
Urethritis asked 25/9, 2018 at 9:59
2
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As described in this question:
OpenJDK vs Java HotspotVM
Oracle's commercial Hotspot JVM is essentially OpenJDK, plus several commercial-client-only features.
But - do these extra features actua...
Hagy asked 19/8, 2018 at 9:26
1
Suppose I have following code snippet with two threads accessing same method with two critical sections (synchronized statements). Each of these synchronized statements is given a different lock ob...
Gravois asked 20/6, 2018 at 20:47
1
Solved
Here are the two samples I would like to base my question on (assuming you have JOL here):
Layouter layout32Bits = new HotSpotLayouter(new X86_32_DataModel());
Layouter layout64BitsComp = new HotS...
Selfforgetful asked 24/5, 2018 at 12:12
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