jvm-hotspot Questions
1
Solved
From reading a rather mature Oracle blog entry, I learned that
(...) the permanent generation is currently collected serially.
However, this blog entry is from quite some years ago and I was w...
Christmann asked 8/12, 2013 at 12:22
1
Solved
I have a 64 bit machine, theoritically the address space is 2^64 bytes and it has 32 G of physical RAM.
this is a server scale machine with 16 cores and is a production server.
Since there is n...
Asseverate asked 6/12, 2013 at 17:21
2
When I run my timing test program in Java Hotspot client, I get consistent behavior.
However, when I run it in Hotspot server, I get unexpected result.
Essentially, the cost of polymorphism is unac...
Semipalmate asked 8/11, 2013 at 6:24
2
Solved
When the jvm (hotspot in my case) permanently compiles certain code paths into machine code, where is that machine code being stored? in the .text segment of process memory? in the process's heap??...
Alcalde asked 25/6, 2013 at 21:8
2
Solved
Suppose we have 3 methods: method 2 is called from method 1, method 3 is called from method 2.
Methods 2 and 3 are of size 30 bytecodes each. Also, suppose for definiteness method 2 is always calle...
Begun asked 11/9, 2013 at 9:43
1
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HotSpot's tiered compilation uses the interpreter until a threshold of invocations (for methods) or iterations (for loops) triggers a client compilation with self-profiling. The client compilation ...
Expellant asked 20/8, 2013 at 21:15
1
Solved
I am dumping heap (OpenJDK 7) on OOM with
-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp/jvm.hprof
startup opts for my VM. I dont have enough space on the disk and cant afford to store m...
Erle asked 14/8, 2013 at 15:44
1
I'm currently evaluating the G1 garbage collector and how it performs for our application. Looking at the gc-log, I noticed a lot of collections have very long "Scan RS" phases:
7968.869: [GC paus...
Micrography asked 12/7, 2013 at 12:18
1
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I recently read a blog entry by Jeremy Manson (Google), about how a more accurate and lightweight asynchronous sampling profiler. It relies on the "AsyncGetCallTrace" undocumented method in hotspot...
Rhombohedral asked 12/7, 2013 at 9:33
1
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Does Java JIT compile the bytecode with the same optimizations at every run on the same machine?
Does it take into consideration dynamic factors like CPU usage at a given moment, or it will make t...
Discommode asked 28/6, 2013 at 17:20
1
Based on the discussions around an answer to this question, I discovered a really strange behaviour of the Java Hotspot optimizer. The observed behaviour can at least be seen in the Oracle VM 1.7.0...
Myth asked 12/3, 2013 at 14:20
2
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What is Klass & KlassKlass in JVM Hotspot Implementation?
As far as I understood from the article Presenting the Perm Generation, Klass is the internal representation of a Java class (let's sa...
Omnibus asked 23/5, 2013 at 18:11
1
As far as I know an object's hash code is normally stored in the header word of the object, which, for example, may have the following layout in HotSpot:
| hash code | age | 0 | 01 |
According to...
Aurel asked 5/2, 2013 at 21:56
2
Solved
I have been micro benchmarking the following code and I noticed something interesting that I am hoping somebody can shed more light on. It leads to a situation where it looks like a for loop can ca...
Broaddus asked 11/4, 2013 at 9:8
4
Java garbage collection and atomic events/stop gc pauses interrupting a sequence of functional calls
I have a complex large multithreaded application to which I am introducing new functionality.
I have added a call to a piece of specialist hardware (via a vendor supplied JNI lib). However before ...
Novercal asked 26/3, 2013 at 11:24
1
In Java theoretically you can throw only Throwables.
This is allowed by the language and checked during class-loading. But if you disable class checking
java -Xverify:none -cp . BadClassTh...
Richela asked 4/3, 2013 at 11:5
2
Solved
I'm trying to figure out if there's a way to determine the JVM startup properties from within a running java process. Specifically I'm trying to find out where parameters such as -Xmx (max heap siz...
Ursala asked 5/10, 2009 at 3:59
1
We are encountering some strange JVM performance issues.
We have a large and somewhat opaque GUI component (Actuate Formula 1 spreadsheet).
If we initialize all of it from the Event Dispatch Thre...
Elegit asked 9/1, 2013 at 9:41
5
Solved
Say we have the following classes:
class DoubleOhSeven {
public static void doSomethingClassy();
public static void neverDoThisClassy();
}
class Dude {
public void doSomething();
public void ...
Viehmann asked 24/11, 2012 at 8:46
3
If you get the stack dump of a process, e.g., via jstack, you get information about locked monitors (and synchronizers) with an address for each. E.g., from a trivially deadlocked two-thread proces...
Tolerate asked 30/10, 2012 at 0:54
2
Solved
Has anyone managed to use the Concurrent Mark Sweep garbage collector (UseConcMarkSweepGC) in Hotspot with more than 120GB RAM?
The JVM starts just fine if I set -ms and -mx to 120G, but if I set t...
Waylay asked 17/6, 2012 at 20:37
5
Solved
Possible Duplicate:
Why doesn't the JVM cache JIT compiled code?
I understand that JIT compilation is compilation to native code using hotspot mechanisms, which can be very very f...
Typhus asked 25/7, 2012 at 14:51
1
Solved
What does the HotSpot JVM flag -XX:+UseCompressedOops do and when should I use it? What sort of performance and memory-usage differences will I see when using it on a 64-bit Java instance (vs. not ...
Livre asked 15/6, 2012 at 16:15
4
Solved
I'm trying to figure out what can cause this error in Java:
Invalid access of stack red zone 0x115ee0ed0 rip=0x114973900
Has anyone ever encountered this error message? It's literally killing th...
Krill asked 1/10, 2009 at 3:35
2
Solved
I am running a server application using JVM sunjava-1.6.0_21.
My application is data heavy and acts as a cache server. So it stores a lot of long living data that we do not expect to get GC throug...
Ladonnalady asked 7/6, 2012 at 3:10
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