I've recently ran into a deployment issue with a call to Mac.getInstance("HmacSHA1").
It can take up to 10 minutes to execute that single call on this specific server, whilst on other machines its execution is instant.
CPU usage also spikes during the call.
Here's a bit of details on the server:
OS: CentOS 5.6 Final (kernel 2.6.35.8-16, i686);
JVM: Sun's JDK 1.6.0_25 (32bit);
CPU: Intel Core2 Duo CPU (E8400#3.00GHz);
Mem: 2GB of RAM;
Dedicated physical server.
Any clues on what might be the problem here?
I suspect you're low on system entropy for secure random numbers. See this page to check: Check available entropy in Linux. And this question has answers to consider: How to solve performance problem with Java SecureRandom? In particular this Java option should help you:
-Djava.security.egd=file:/dev/./urandom
It's much faster, but slightly less secure.
Related
I have been running OptaPlanner application on Linux servers which takes total 10 minutes.
However, when I move it to run on Solaris server the total processing time become more than 50 minutes.
And the Solaris(SPARC-T5) has more CPUs and memory than Linux(Intel).
So, I am wondering is there any settings to be done to use OptaPlanner on Solaris os?
What can be the possible reasons for this issue?
Thanks in advance for your time and answers.
Interesting observation - I 'd like to understand what happens there too.
Create a benchmark config for your use case (if you haven't already), run it on both machines and share both benchmark html reports here. I'll diagnose them.
Typical causes can be: JDK version differences, JVM -server mode, undetermined termination config (unimprovedTimeLimit), ...
But none of that explains a 5x difference.
I have performance issues in Isabelle (i.e., the resent version Isabelle2013-2).
I use Isabelle/JEdit, based on the new interface.
So before, the situation was I had some trouble with the performance. But now it is worse, as I sometimes have to wait up to 10 seconds sometimes to enter the right. The performance issues get worse over time, to the point were I have to restart Isabelle after an hour or so.
My suspicion is that I can configure Isabelle better or apply some tricks that improve the performance.
Hardware:
recent CPU, it's an intel i7 quadcore (mobile labtop chip), 16GB ram, fast SSD harddisk.
Software:
64bit arch linux (kernel 3.12.5-1-ARCH)
no 32bit compatibility libraries
my java version is:
java version "1.7.0_45"
OpenJDK Runtime Environment (IcedTea 2.4.3) (ArchLinux build 7.u45_2.4.3-1-x86_64)
My theory file has the size 125KB, the whole theory I am working is in one file, but at the moment I would really want to have just one file.
Symptoms:
Isabelle displays only about 900mb in the lower right corner of UI. I have 16GB RAM, should I configure java to use more RAM? Sometimes a singe process consumes 600% of the CPU, i.e., 6 cores that the linux kernel sees.
Tricks I use:
One trick is that I insert *) at a line below the code I am working on. This leads to a syntax error and the below code is not checked. The second trick is that I went to the timing panel, and all proofs that took longer than 0.2 seconds I commented out and replaced with sorry.
The resent two Isabelle versions are really great improvements!
Any suggestions or tricks to how I can improve the performance of Isabelle?
A few general hints on performance tuning:
One needs to distinguish Isabelle/ML (i.e. the underlying Poly/ML runtime) versus Isabelle/Scala (i.e. the underlying JVM).
Isabelle/ML: Intel CPUs like i7 have hyperthreading, which virtually doubles the number of cores. On smaller mobile machines it is usually better to restrict the nominal number of cores to half of that. See the "threads" option in Isabelle/jEdit / Plugin Options / Isabelle / General. When running on batteries you might even go further below.
Isabelle/ML: Using x86 (32bit) Poly/ML generally improves performance. This is only relevant to Linux, because that platform usually lacks x86 libraries that other platforms provide routinely. There is rarely any benefit to fall back on bulky x86_64. Poly/ML 5.5.x is very good at working in the constant space of 32bit mode.
Isabelle/Scala: JVM performance can be improved by using native x86_64 (which is the default) and providing generous stack and heap parameters.
The main Isabelle application bundle bootstraps the JVM with some options that are hard-wired in a certain place, which can be edited nonetheless:
Linux: Isabelle2013-2/Isabelle2013-2.run
Windows: Isabelle2013-2/Isabelle2013-2.ini
Mac OS X: Isabelle2013-2.app/Contents/Info.plist
For example, the maximum heap size can be changed from -Xmx1024m to -Xmx4096m.
The isabelle jedit command-line tool is configured via the Isabelle settings environment. See also $ISABELLE_HOME/src/Tools/etc/settings for some examples of JEDIT_JAVA_OPTIONS, which can be copied to $ISABELLE_HOME_USER/etc/settings and adapted accordingly. It is also possible to monitor JVM performance via jconsole to get an idea if that is actually a source of problems.
Isabelle/Scala: Isabelle bundles a certain JVM, which is assumed here by default. This variable elimination of Java versions is important to regain some sanity --- otherwise you never know what you get. Are you sure that your OpenJDK is actually used here? It is unlikely, unless you have edited some Isabelle settings.
Further sources of performance problems on Linux is graphics. Java/AWT is known to be much slower on X11 than on Windows and Mac OS X. Using the quasi-native GTK look-and-feel on Linux degrades graphics performance even further.
I have developed a Java application that normally run on Linux. It's a POJO application with Swing. Performance is reasonably good.
Now I tried to run it on Windows XP with 2Gb RAM, in a machine with similar or greater potency, and performance is much worse. I observe that it uses 100% CPU.
For example:
A process that creates a window very heavy, with many components: Linux 5 seconds, Windows 12.
A process that accesses a PostgreSQL DB with a heavy query (the server and the JDBC driver are the same): 23 seconds Linux, Windows 43.
I tried also with a virtualized Windows machine with similar features, and the result is significantly better!
Is it normal? What parameters can I assign to improve performance?
Unless you are comparing Linux and Windows XP on the same machine it is very hard to say what the difference is. It could be that while the CPU is faster, the GFX card and disk subsystem is slower.
Java passes all of this IO and GFX acitvity to the underlying OS and the only thing you can do differently is to do less work or work more efficiently. This is likely to make both systems faster, as there is not particular to one OS which you can tune.
Try running Java Visual VM (which is distributed as part of the JDK): attach to your application, then use the CPU Profiler to determine precisely where all that CPU time is going.
There may be subtle differences in the behavior of JRE parts (Swing comes to mind), where the JRE responds very unforgiving to a bad practice (like doing thing from the wrong thread in Swing).
Since you have no clues, I would try profiling the same use case in both environments and see if any significant differences turn up where the time is spent. This will hopefully reveal a hint.
Edit: And ensure that you do not run Windows with brakes on (aka. Antivirus and other 'useful' software that can kill system performance).
Hi I'm trying to test my JAVA app on Solaris Sparc and I'm getting some weird behavior. I'm not looking for flame wars. I just curious to know what is is happening or what is wrong...
I'm running the same JAR on Intel and on the T1000 and while on the Windows machine I'm able to get 100% (Performance monitor) cpu utilisation on the Solaris machine I can only get 25% (prstat)
The application is a custom server app I wrote that uses netty as the network framework.
On the Windows machine I'm able to reach just above 200 requests/responses a second including full business logic and access to outside 3rd parties while on the Solaris machine I get about 150 requests/responses at only 25% CPU
One could only imagine how many more requests/responses I could get out of the Sparc if I can make it uses full power.
The servers are...
Windows 2003 SP2 x64bit, 8GB, 2.39Ghz Intel 4 core
Solaris 10.5 64bit, 8GB, 1Ghz 6 core
Both using jdk 1.6u21 respectively.
Any ideas?
The T1000 uses a multi-core CPU, which means that the CPU can run multiple threads simultaneously. If the CPU is at 100% utilization, it means that all cores are running at 100%. If your application uses less threads than the number of cores, then your application cannot use all the cores, and therefore cannot use 100% of the CPU.
Without any code, it's hard to help out. Some ideas:
Profile the Java app on both systems, and see where the difference is. You might be surprised. Because the T1 CPU lacks out-of-order execution, you might see performance lacking in strange areas.
As Erick Robertson says, try bumping up the number of threads to the number of virtual cores reported via prstat, NOT the number of regular cores. The T1000 uses UltraSparc T1 processors, which make heavy use of thread-level parallelism.
Also, note that you're using the latest-gen Intel processors and old Sun ones. I highly recommend reading Developing and Tuning Applications on UltraSPARC T1 Chip Multithreading Systems and Maximizing Application Performance on Chip Multithreading (CMT) Architectures, both by Sun.
This is quite an old question now, but we ran across similar issues.
An important fact to notice is that SUN T1000 is based on UltraSpac T1 processor which only have 1 single FPU for 8 cores.
So if you application does a lot or even some Float-Point calculation, then this might become an issue, as the FPU will become the bottleneck.
I made the observation that my java application is running much faster when executed on an AMD processor in contrast to an Intel CPU.
For example my JBoss starts in about 30 seconds on a 3 GHz AMD processor and needs about 60 seconds on a 3 GHz Intel processor with identical disc, RAM and OS?
Has anyone else made this observation? Why is this so?
It depends on the CPU generation as well - clock speed is not everything.
If you set up e.g. an Intel Pentium 4 and an AMD Phenom with the same clock speed, you'll see a large difference in favour of the Phenom.
Update: If you're really curious, use a profiler and post the results.
Other considerations:
Size of processor on-board cache
Bus speed of your motherboard
Cache size of your hard drive
Hard drive RPM and read speed
Bottom line: Unless your configurations are identical besides the chips, and you are trying to asses the performance of a particular technology, you're really comparing apples to oranges.
Are they both running the same architecture? Or is the AMD running a 64-bit OS?
Remember that startup time isn't everything; a 60s startup time probably isn't that bad if the application runs as fast AFTER it's started up.
I've seen 64-bit JDK work much faster than 32-bit one on the same processor. So maybe that's the case.
EDIT: http://java.sun.com/docs/hotspot/HotSpotFAQ.html#64bit_performance. Sorry, I guess I'm wrong.