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Java VisualVM profiling freezing issue

I am using java visualVM 1.4 to do JDBC profling for my application, i need to do the following:
1-Start profiling
2-Take snapshot
3-Clear profiling records go back to step 1
I need to perform the previous loop for around 10 times, i am using my local-machine to do the entire work.
So i do the steps successfully for two times after that either ther visualVM freezes or the java process i am profiling freezes, and my only solution is to restart both process and do the work again.
I tried to read logs for visualVM and noticed that i see the following exception:
java.io.IOException: Can not attach to current VM
at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.<init>(HotSpotVirtualMachine.java:75)
at jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:58)
at jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
at jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
at com.sun.tools.visualvm.attach.AttachModelImpl.getVirtualMachine(AttachModelImpl.java:124)
Caused: java.io.IOException: Can not attach to current VM
at com.sun.tools.visualvm.attach.AttachModelImpl.getVirtualMachine(AttachModelImpl.java:126)
I am using jdk 8_152 for both the JVM and the java process.

Automatically launching a pre-set configuration in VisualVM

I am trying to profile functions in my java application using VisualVM (eclipse plug-in). Right now when I run an application, eclipse opens VisualVM and takes me to the profilers tab where I can start profiling by pressing the CPU or Memory buttons. Unfortunately, in the time that I take to manually do this, I lose significant number to iterations in my application to get a precise result.
I know I can set the default profiler setting for an application under Tools->Options->Profiling. But is there an option in VisualVM where it can automatically fire the profiler on seeing a particular main function/application being launched.

Profile Entire Java Program Execution in VisualVM

In Java profiling, it seems like all (free) roads nowadays lead to the VisualVM profiler included with JDK6. It looks like a fine program, and everyone touts how you can "attach it to a running process" as a major feature. The problem is, that seems to be the only way to use it on a local process. I want to be able to start my program in the profiler, and track its entire execution.
I have tried using the -Xrunjdwp option described in how to profile application startup with visualvm, but between the two transport methods (shared memory and server), neither is useful for me. VisualVM doesn't seem to have any integration with the former, and VisualVM refuses to connect to localhost or 127.0.0.1, so the latter is no good either. I also tried inserting a simple read of System.in into my program to insert a pause in execution, but in that case VisualVM blocks until the read completes, and doesn't allow you to start profiling until after execution is under way. I have also tried looking into the Eclipse plugin but the website is full of dead links and the launcher just crashes with a NullPointerException when I try to use it (this may no longer be accurate).
Coming from C, this doesn't seem like a particularly difficult task to me. Am I just missing something or is this really an impossible request? I'm open to any kinds of suggestions, including using a different (also free) profiler, and I'm not averse to the command line.

Consider using HPROF and opening the data file with a tool like HPjmeter - or just reading the resulting text file in your favorite editor.
Command used: javac -J-agentlib:hprof=heap=sites Hello.java
SITES BEGIN (ordered by live bytes) Fri Oct 22 11:52:24 2004
percent live alloc'ed stack class rank self accum bytes objs bytes objs trace name
1 44.73% 44.73% 1161280 14516 1161280 14516 302032 java.util.zip.ZipEntry
2 8.95% 53.67% 232256 14516 232256 14516 302033 com.sun.tools.javac.util.List
3 5.06% 58.74% 131504 2 131504 2 301029 com.sun.tools.javac.util.Name[]
4 5.05% 63.79% 131088 1 131088 1 301030 byte[]
5 5.05% 68.84% 131072 1 131072 1 301710 byte[]
HPROF is capable of presenting CPU usage, heap allocation statistics,
and monitor contention profiles. In addition, it can also report
complete heap dumps and states of all the monitors and threads in the
Java virtual machine.

The best way to solve this problem without modifying your application, is to not use VisualVM at all. As far as other free options are concerned, you could use either Eclipse TPTP or the Netbeans profiler, or whatever comes with your IDE.
If you can modify your application, to suspend it's state while you setup the profiler in VisualVM, it is quite possible to do so, using the VisualVM Eclipse plugin. I'm not sure why you are getting the NullPointerException, since it appears to work on my workstation. You'll need to configure the plugin by providing the path to the jvisualvm binary and the path of the JDK; this is done by visiting the VisualVM configuration dialog at Windows -> Preferences -> Run/Debug - > Launching -> VisualVM Configuration (as shown in the below screenshot).
You'll also need to configure your application to start with the VisualVM launcher, instead of the default JDT launcher.
All application launches from Eclipse, will now result in VisualVM tracking the new local JVM automatically, provided that VisualVM is already running. If you do not have VisualVM running, then the plugin will launch VisualVM, but it will also continue running the application.
Inferring from the previous sentence, it is evident that having the application halt in the main() method before performing any processing is quite useful. But, that is not the main reason for suspending the application. Apparently, VisualVM or its Eclipse plugin does not allow for automatically starting the CPU or memory profilers. This would mean that these profilers would have to be started manually, thereby necessitating the need to suspend the application.
Additionally, it is worth noting that adding the flags: -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=y to the JVM startup will not help you in the case of VisualVM, to suspend the application and setup up the profilers. The flags are meant to help you in the case of profilers that can actually connect to the open port of the JVM, using the JDWP protocol. VisualVM does not use this protocol and therefore you would have to connect to the application using JDB or a remote debugger; but that would not resolve the problem associated with profiler configuration, as VisualVM (at least as of Java 6 update 26) does not allow you to configure the profilers on a suspended process as it simply does not display the Profiler tab.

This is now possible with the startup profiler plugin to VisualVM.

The advice with -Xrunjdwp is incorrect. It just enables debugger and with suspend=y it waits for debugger to attach. Since VisualVM is not debugger, it does not help you. However inserting System.in or Thread.sleep() will pause the startup and allows VisualVM to attach to your application. Be sure to read Profiling with VisualVM 1 and Profiling with VisualVM 2 to better understand profiler settings. Note also that instead of profiling, you can use 'Sampler' tab in VisualVM, which is more suitable for profiling entire java program execution. As other mentioned you can also use NetBeans Profiler, which directly support profiling of the application startup.

monitor Java process memory in realtime

I have a java application that its memory starting to jump and fall after few days.
Is there a tool that can show me the variables/members sizes during run/debug in real time?
Debugging it with eclipce is impossible.

Check out jhat and jmap.
In the longer run, consider adding a monitor to your app (with JMX, or write your own). It may help you in many situations in future.

Install this: http://visualvm.java.net/eclipse-launcher.html and then launch using Eclipse. This does not use the debugger, but launches the VisualVM application which lets you monitor the app. You'll need to go into the Run Configurations.. settings to set this up, and select VisualVM launcher at the bottom (Select Other... -> VisualVM launcher). You'll need to go into Preferences to set up the location of VisualVM too.
(On later Eclipse versions, drop it into the drops folder, unpacked).

If you're using >JDK6 and can get access to the machine then jvisualvm.exe may work, part of the JDK (in the bin dir)

yourkit (http://www.yourkit.com/) can do that, but expect a HUGE degradation on the performance of the app, as it has to track the size of each object.
I think it's better if you run yourkit with a few less invasive options, and then you can take snapshots of the memory usage.
I forgot to add, that with yourkit you can run the application without almost any instrumentation (which will slightly degrade the performance of the app) and when the problems start ocurring, you can enable the more heavy weight profiling while the app is running.

Why does Tomcat 5.5 (with Java 1.4, running on Windows XP 32-bit) suddenly hang?

I've been running Tomcat 5.5 with Java 1.4 for a while now with a huge webapp. Most of the time it runs fine, but sometimes it will just hang, with no exception generated, and no apparant way of getting it to run again other than re-starting Tomcat. The tomcat instance is allowed a gigabyte of memory on the heap, but rarely exceeds 300 MB. Has anyone else run into this issue, and is there a solution for it?
For clarification: I determined how much memory it is using via Task Manager and via Eclipse (I've also tried running it outside of Eclipse, but get the same problem eventually, though it takes a little longer). With Eclipse, I look at the memory allocated via its little (optional) memory pane and the amount allocated to javaw.exe via the task manager. I use the sysdeo? tomcat plugin for Eclipse.

For any jvm process, force a thread dump. In windows, this can be done with CTRL-BREAK, I believe, in the console window.
In *nix, it is almost always "kill -3 jvm-pid".
This may show if you have threads waiting on db connection pool/thread pool, etc.
Another thing to check out is how many connections you have currently to the JVM -- either use NETSTAT or SysInternals utility such as tcpconn/tcpview (google it).
Also, try to run with the verbose:gc JVM flag. For Sun's JVM, run like "java -verbose:gc". This will show your garbage collections. If it is collecting a lot (FULL COLLECTIONS, expecially) then you probably have a memory leak. The full collections are costly, especially on large heaps like that.
How are you determining that only 300mb are being used?

It sounds like you're hitting a deadlock.
If you can reproduce it in a dev environment then try attaching a debugger once it's happened. Take a look at your threads and see if you have any deadlocks.
If you can't get a debugger to attach you should be able to generate a thread dump, as Dustin pointed out.

Try increasing the logging sensitivity for the Tomcat application server.
http://tomcat.apache.org/tomcat-5.5-doc/logging.html
You can increase the sensitivity to FINEST or ALL for most of them for a few days and see if that helps you catch anything.

I agree with creating multiple thread dumps and viewing them though this: Thread Dump Analyzer