I am developing a portal based on Liferay and I use Eclipse as IDE. I am running a 64 bit windows 7 with 8gb RAM ddr2 and AMD Athlon II X2 255 3.10 GHz. My computers freezes some time when I run service builder or when I want to open an xml file in eclipse. I checked the Process Manager from Task Manager and I have seen that I have two javaw processes running , jaxaw.exe*32 and javaw.exe.Is this normal. If this is a problem can you help me to fix it. Thanks
One process is for Eclipse itself and the other one is for your application. And no that is not a problem.
That's not problem. In most cases, this is caused by two different jvm processes, one for 32 bit jvm, another for 64bit. It's rarely to see that one process can cause this issue, in fact, I have never seen in my past 15 years java career.
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I have a number of Java processes using OpenJDK 11 running on Windows Server 2019. The server has two physical processors and 36 total cores; it is an HP machine. When I start my processes, I see work allocation in Task Manager across all the cores. This is good. However after the processes run for some period of time, not a consistent amount of time, the machine begins to only utilize only half the cores.
I am working off a few theories:
The JDK has some problem that is preventing it from consistently accessing all the cores.
Something with Windows Server 2019 is causing a problem, limiting Java from accessing all the cores.
There is a thermal management problem and one processor is getting too hot and the OS is directing all the processing to the other processor.
There is some issue with hyper-threading and the 'logical' processors that is causing the process to not be able to utilize all the cores.
I've tried searching for JDK issues and haven't found anything like this mentioned. I went down to the server and while it's running a little warm, it didn't appear excessively hot. I have not yet tried disabling hyper-threading. I have tried a number of parameters to force the JVM to use all the cores and indeed the process initially does use all the cores; I can see the activity in Task Manager.
Anyone have any thoughts? This is a really baffling problem and I'd appreciate any ideas.
UPDATE: I am able to make it use the other processor by using the Task Manager to assign one of the java.exe processes to the other processor. This is also working from the java invocation on the command line as well with an argument for which socket to use.
Now that said, this feels like a hack. I don't see why I should have to manually assign a socket to each of my java processes; that job should be left to the OS. I'm still not sure exactly where the problem is, if it's the OS or what.
I wrote a client server java project using Netbeans on Windows platform. When I profile it on windows it shows 8 threads running but when I run it on Ubuntu, htop shows 21 processes(threads) attached to it. Does anyone know why?
Yes. The numbers mean different things. In Windows there are process and threads. In contrast, Linux uses a 1-1 threading model.
We have bunch of jar files that are Java applications and run just fine. There are a few however that do nothing although it is expected to run :) with a GUI.
Is this a common issue with jar files that some have difficulties to run?
The OS is Windows 7 and the example not working jar is whitebox a free GIS application, BTW.
We reiterate that we have many jar applications that run like a charm in the above system. This means that it should not be a problem with Java installation (latest update 7u40 exists in the system).
We checked almost all jar failure related topics but no one discussing the issue above which is happening for some applications.
We also mention, we uninstalled and reinstalled java many times but with no success. The application whitebox does nothing. In one try, it did run and when we closed it. And we are since then trying to run it again but nothing is happening! Even nothing appears in the running Processes!
We examined command line and double click. No success. The file type association is correct. Furthermore as we said others are working just fine.
The problem reported was due to inadequate RAM. Whitebox requires 2GB RAM to run smoothly. While this is huge we could run it on an old laptop with only 1GB RAM. The solution was to increase the size of paging file (virtual memory) into the range 1024MB and 2048MB. We also moved its location from C drive into other drives. We the settings mentioned it runs without any problem. We have tried it many times and happy to report for this case the problem is now completely solved.
Conclusion:
For some Java applications if something happend as described in the question it may be due to memory requirement. In this case increasing virtual memory could solve the problem without a need to buy additional RAM.
I was working on a kind of SMTP kinda protocol, I made it in java and run successfully. It was consuming about 20 to 30 MB in my laptop. Later I decided to make the protocol live on internet. I purchased the servers(VPS), domain. It costed me a lot. But when I tried to run my program over that server I was so shocked that my program was consumption about 800 to 900 MB for each class I was running. I thought it may be my programming fault, I tried a lot to recover from problem but I could not. Later a friend of mine suggested me to test a simple Hello word program on same server, I was so shocked that even that program was eating up to 900 MB of my total RAM.
What kinda of problem can it be ?
Is it the fault in those servers, or their OS and kernels versions ?
Is it problem of JVM with Linux kernels or older linux kernels.
I have even tried with older JVMs but no use. :(
I tried most of popular flavors of Linux but it worked same and had exactly same problem on all Linux flavors. Was eating huge memory in all cases. ( All of them had Linux kernel 2.6.xx)
But it worked very smooth and consumed expected memory in my laptop. (about 30 to 50 Mb). I use Linux in my laptop. But the difference is that my kernel is above 3.1.xx . Can it be the problem ? I am really so disappointed with behavior of my servers and have lost lots of money in it. Please anybody tell me the possible solutions, can it be the problem of Linux kernel or its problem in my programming.
Is your laptop running Windows? I'll assume that the answer is yes. The memory values you see reported in Windows Task Manager are not what Linux reports for total resident memory.
I don't believe that Hello World is taking up 900 MB. If it is, that tells me that the JVM memory is being reported, not your app.
Are you running this app on a Java EE app server like Tomcat or JBOSS? That will make a very big difference indeed.
The best advice is to search SO for other questions that showed how to use Linux tools like nmap to figure out where memory is being consumed.
HI All,
I am working on WAS 7 and i am using windows 7 operating system and IE9 so can anyone suggest me what kind of good PC configuration i needed because my PC is getting hanged when i started worked on this... so PC Configuration will be like RAM ? processor ? like that...
Look at this for the bare minimum requirements.
http://www-01.ibm.com/support/docview.wss?rs=180&uid=swg27012421
Ensure that the memory is far higher than what is stated in this document. 1 GB is certainly not adequate.
It also depends on what you are running on this box (besides WebSphere App Server)
How many instances (or servers) of WAS are you running on it. Have about 1.5 GB (not referring to the JVM Heap here but the whole java process) per server instance as a ball park to have a reasonable performance.
HTH
Manglu