I've done some search out there but couldn't find too much really helpful info on it, but could someone try to explain the basic of Java memory maps? Like where/how to use it, it's purpose, and maybe some syntax examples (inputs/outputs types)? I'm taking a Java test soon and this could be one of the topics, but through all of my tutorials Jmap has not come up. Thanks in advance
Edit: I'm referring to the tool: jmap
I would read the man page you have referenced.
jmap prints shared object memory maps or heap memory details of a given process or core file or a remote debug server.
NOTE: This utility is unsupported and may or may not be available in future versions of the JDK. In Windows Systems where dbgeng.dll is not present, 'Debugging Tools For Windows' needs to be installed to have these tools working. Also, PATH environment variable should contain the location of jvm.dll used by the target process or the location from which the Crash Dump file was produced.
http://docs.oracle.com/javase/7/docs/technotes/tools/share/jmap.html
Its not a tool to be played with lightly. You need a good profiler which can read it output as jhat is only useful for trivial programs. (YourKit works just fine for 1+ GB heaps)
Related
Sometimes in s/w companies, customers provide data in multiple formats. There are linkable and executable data that are said to be "Rehosted" and compiled object files that are said to be "Retargeted". I am trying to understand what rehosting and retargeting mean in this area. Is it similar to the Bootstrap theory in computer science? I have the understanding of the following process (if not incorrect):
PROBLEM:
I need to write a compiler for a new language called "MyLang" to run on PowerPC
Solution:
1. I need to write a compiler for a language "MyLang-Mini"; a subset of "MyLang" to run on PowerPC.
2. I need to write a compiler for "MyLang" using "MyLang-Mini" to run on PowerPC.
3. I run the compiler obtained from no. 1 through the compiler obtained from no. 2 to
obtain the compiler for MyLang to run on PowerPC.
IN BESPOKE "T" DIAGRAM (...ISH):
MyLang PowerPC MyLang PowerPC
MyLangMini MyLangMini PowerPC PowerPC(instr.)
PowerPC(instr.)
What I am getting confused about is rehosting and retargeting. How are they coonected to this concept? What am I rehosting and retargeting if I have some binary data such as .exe or .obj? I would appreciate some detailed explanation if possible please!
I know that this will embark onto "CROSS-COMPILERS", but would prefer expert opinions to be sure.
Thanks in advance.
I now know that in s/w engineering:
REHOSTING - If you have a third-party application linkable/executable that requires usage on your host machine, you do rehosting. The target in this case are most often the same (OS platform, processor, etc.). In worst case, there is a virtualisation required. The rehosted application will run as if it was one of the application running in the host machine
RETARGETTING - If you have a third-party source code, you might need to recompile that to match with your target environment. It may also be that you have third-party .o or .obj compiled models and you want to link them with your source code (retargeted) in order to host it on a host machine. Just like REHOSTED application, it will be as if the application was installed on the host machine.
It will be good to know how this is similar to the compiler rehosting and retargeting. Sorry, I am a newbee is this area and will appreciate even a slap on the wrist.
Users have been reporting problems/crashes/bugs that I can't reproduce on my machine. I'm finding these problems difficult to fix.
I've started using EurekaLog (fantastic!) and SmartInspect. Both these tools have helped greatly but I'm still finding it difficult to catch some problems.
I've just purchased Debugging by David Agans (and waiting for it to arrive).
Are there any other tools or techniques specific to Delphi that will help with catching these hard to find remote problems? The kinds of problems I'm finding difficult to track down are those that don't raise exceptions or have a clear cause. EurekaLog catches exceptions and SmartInspect is pretty good once I have a theory to check. But in some cases it is a seemingly random crash and there are several thousand lines of code that may may be at fault. How to narrow down to the root cause?
MadExcept is what I use, and it is fabulous. I have also used EurekaLog and find the functionality almost exactly identical, except that I have more experience and time using MadExcept. it's free for non-commercial use, and reasonably priced for commercial use.
Update: MadExcept 4 is now out and even supports 64 bit Delphi XE2 apps, and has memory-leak checking too.
When nothing blows up, I rely on heavy use of trace logging. I have a TraceMessage(integer,string) function which I call throughout all my apps, and when someone has problems I get them to click a menu item that turns up the debug trace level to the most verbose level; it gives me a complete history of everything my application did, and this has helped me even more than madExcept, to solve problems at customer sites. Customers get a crash, and that crash report sent by madexcept contains a log file (created by my app) that is attached automatically. I believe you can do this equally well with madExcept and EurekaLog. If you need a logging system you could download Log4D, or you could write your own, it's pretty simple.
For always-free, try JclDebug, which requires more work to set up, but which has worked fabulously for me, also.
For help with heap problems, learn more about fastMM (full version) debug options.
And you shouldn't forget that Delphi itself supports Remote debugging, if you can reproduce a crash on machines in your office that don't have delphi installed, use remote debug across the office network instead of installing a complete RAD Studio installation on that other machine at your work. You could also use remote debug to connect to a client PC computer across the internet, but I have not tried remote debug across the internet yet, so I can't say whether it works great over the internet or not. I do know that since remote debug doesn't support automatic deploy of the EXE file you built (you have to do that part yourself), remote debug over internet, to a client PC is more work.
You might also find lots of your problems by fixing all your hints and warnings, and then going through with CodeHealer or Pascal Analyzer (PAL) from Peganza. These static analysis tools can help you find real code problems.
If performance and memory usage are your problems, get the full version of AQTime, and use it to profile and watch your system operate. It will help you fix your memory leaks, and understand your app's runtime behaviour and memory usage, not just leaks but bottlenecks for memory and CPU usage. Some of those bottlenecks can also be the source of some odd problems. I have even used AQTime to help me find deadlocks, since it can generate traces of execution, that can help me figure out what code is running, and locate deadlocks. Update: AQTime is not installable on machines other than your main dev machine, without violating the newly modified license terms for AQTime. These terms were never this restrictive in the good old days.
If you gave more exact idea of what your problems are, I'm sure other people could give you some more ideas that are specific, but all of the above are general techniques that have served me well.
One of the best way is to use the Remote Debugger that comes with Delphi, so you can debug directly the application running on the remote machine. THe remote debugger is somewhat buggy in some Delphi releases, and requires to follow the instructions carefully to make it working, but when needed it's a tool to consider. Also check if there are updates available for your version, they could come in a separate installer for deployment on "remote" systems. Otherwise first install the remote debugger, than check if the files installed has newer versions in your local installation, and the copy tehm on the remote machine.
CodeSite has helped me a lot in these situations. Since XE it is bundled with Delphi.
Logging is the key, in this matter.
Take a look at our TSynLog class available in our Open Source SynCommons library.
It does have the JCL Debug / MadExcept features, with some additional (like customer-side profiling, and logging):
logging with a set of levels;
fast, low execution overhead;
can load .map file symbols to be used in logging;
compression of .map into binary .mab (900 KB -> 70 KB);
inclusion of the .map/.mab into the .exe;
reading of an external .map to add unit names and line numbers to a log file without .map available information at execution;
exception logging (Delphi or low-level exceptions) with unit names and line numbers;
optional stack trace with units and line numbers;
methods or procedure recursive tracing, with Enter and auto-Leave using interfaces;
high resolution time stamps, for customer-side profiling of the application execution;
set / enumerates / TList / TPersistent / TObjectList / TContainer / dynamic array JSON serialization;
per-thread or global logging;
multiple log files on the same process;
integrated log archival (in zip or any other format);
Open Source, works from Delphi 5 up to XE.
I'd like to see if I can reduce VM latencies by using Mono's AOT (ahead of time compiler). How does one run the .so files? (Sorry this is question is so rudimentary; I couldn't find a simple answer on Mono's documentation).
I figured out how to use mkbundle (mkbundle2 in this case), but are the resulting files being optimized? The Mono AOT documentation mentions "-O=all,-shared" flags, but I don't see these for mkbundle.
Though it's probably a much different answer, if there are good ways of keeping the VM open (with something more natural / platform neutral than a fifo special file), that might be best.
Thanks in advance!
If the AOT .so files exist beside the exe/dll files, Mono will use them when you run the exe. But you still need the dll/exe files for metadata and things that cannot be AOT-compiled.
Not sure if it's exactly related to your question, but see the final note here
Link
about the --resident flag to the compiler, to make fsc.exe faster on Mono.
I am attempting to use WinDBG or another debugger to debug a CodeGear Delphi 2007 Windows application on a remote machine. I have been unable to produce symbol files for WinDBG.
Is there a way to use WinDBG or another debugger to debug Delphi applications on a system that doesn't include the IDE?
Edit1
The remote debugger is not an option here. I am able to remote in to the end user PC, but I am unable to use the remote debugger due to firewall restrictions.
Edit2
I am able to remote in to the machine, but can not connect the CodeGear remote debugger due to firewall restrictions.
How about the remote debugger? Build your app with remote debug symbols and debug from your development machine across the network.
instead, i rely on MadExcept stack tracing and some logging features. my application is distributed worldwide & this has been sufficient.
You can try generating a map file and then convert it to a dbg file using map2dbg from
http://code.google.com/p/map2dbg/
Then you can load the dbg file in WinDbg.
Disclaimer: I had faced a similar issue but I managed to do remote debugging and didn't have to do all this. So I am not sure this will work. But if you try it then do let us know if it works.
I'm afraid this is one more of those "I don't have an actual answer" answers, but it might just help...
Have you considered adding logging to your application? I've heard great things about SmartInspect. With it, you can log all sorts of information, including stack traces and "watches" (variables).
Another logging product for Delphi is EurekaLog.
In Delphi you could use Run -> Attach to Process, select the remote machine and select the process you'd like to debug.
http://sourceforge.net/projects/tds2dbg/ can be used to convert Delphi's TDS debug files to DBG files. This gives basic symbol information -- functions, classes, units, but not variables. Enough for a reasonable call stack, and with a bit of knowledge, enough to debug Delphi apps live and with dumps.
I've written about some of Delphi+WinDBG experiences on my blog: https://marc.durdin.net/2015/11/windbg-and-delphi-a-collection-of-posts/
Thank you all for the great suggestions and interesting products.
To solve this specific issue, the "best" way I found uses the OutputDebugString located in the Windows namespace. This, along with Debug View from Sysinternals, will allow me to gather debug information and sort through it pretty quickly.
If you decide to use this method, make sure everything is wrapped in ANSI formatting. IE:
OutputDebugString(PAnsiChar(string1 + string2));
This makes sure that string1 and string2 are combined and then converted in to ANSI Characters.
I probably should have just started dumping text to a file for something quick and dirty, but this will allow a non-debugging version to emit debugging messages.
How to generate the Symbols file of a PowerBuilder program for dump analysis?
Are you running into a problem with a compiled PowerBuilder application?
I've never used the Microsoft debugger, however, I have used Dependency Walker and ran my app from within that environment. Usually that helps us if we have missing deployables, etc.
If you need a stack dump, have you thought about running the app from the Run window and adding the /debug option after the name of the app? That creates a call stack log that shows all your commands being called, etc. Probably would get you what you need.
Please advise.
You can install Dr. Watson (drwtsn32) to automatically create a crash dump when/if your application dies.
That said, the dump will usually only be useful if you are calling into native DLL's. Otherwise the stack will just include various PBVM calls that will be difficult to correlate back to actual source code lines.