Valgrind suppression file for java

The memory is still reachable, so the program could still be using it. In theory, you could free it at the end of the program, but all memory is freed at the end of the program anyway. Although still reachable memory isn't a real issue in theory, you might still want to look into it. You might want to see whether you could free a given block earlier, which might lower memory usage for longer running programs. Or because you really like to see that statement All heap blocks were freed -- no leaks are possible.

Now you will also get backtraces showing where still reachable memory blocks were allocated in your program. To explore the other categories of leaks, we change our program a little to include some lists of numbers to report. Each report will have a different list of numbers to report. The complete data structure is allocated at the start of the program.

And for each set of numbers, we allocate a new block of numbers. To keep things simple too simple, as Memcheck will point out we keep just one pointer to the current numbers struct to be printed. Although we create three sets of numbers, we output only two reports:. When we compile this program with gcc -Wall -g -o possibly possibly.

Memcheck calls this memory possibly lost because it can still see how to access the blocks of memory. The numbers pointer points to the third block of numbers.

If we kept some extra information, we could theoretically count backward to the beginning of this block of memory and access the rest of the information, or deallocate the whole block and the other memory it points to. But Memcheck thinks this is most likely a mistake.

And in our example, as in most such cases, Memcheck is right. When walking a data structure without keeping a reference to the structure itself, we can never reuse or free the structure.

Then, Memcheck would have reported the data blocks as still reachable. There is still a memory leak, but not a severe one, because there is a direct pointer to the memory and it could easily be freed. This is a hook for memory debuggers, so they can ask glibc to free up any memory it has used. Doing that is needed to ensure that Valgrind doesn't incorrectly report space leaks in glibc. Workaround for 1. You may then get space leak reports for glibc allocations please don't report these to the glibc people, since they are not real leaks , but at least the program runs.

If Memcheck the memory checker shows any invalid reads, invalid writes or invalid frees in your program, the above may happen. Reason is that your program may trash Valgrind's low-level memory manager, which then dies with the above assertion, or something similar. The cure is to fix your program so that it doesn't do any illegal memory accesses. The above failure will hopefully go away after that.

One possibility is that your program has a bug and erroneously jumps to a non-code address, in which case you'll get a SIGILL signal. Memcheck may issue a warning just before this happens, but it might not if the jump happens to land in addressable memory. Another possibility is that Valgrind does not handle the instruction. If you are using an older Valgrind, a newer version might handle the instruction. However, all instruction sets have some obscure, rarely used instructions.

Also, on amd64 there are an almost limitless number of combinations of redundant instruction prefixes, many of them undocumented but accepted by CPUs. So Valgrind will still have decoding failures from time to time. If this happens, please file a bug report. Valgrind can handle dynamically generated code, so long as none of the generated code is later overwritten by other generated code.

If this happens, though, things will go wrong as Valgrind will continue running its translations of the old code this is true on x86 and amd64, on PowerPC there are explicit cache flush instructions which Valgrind detects and honours. Valgrind will run much more slowly, but should detect the use of the out-of-date code. In practice, Java implementations tend to do nasty things that most programs do not, and Valgrind sometimes falls over these corner cases. First of all: relax, it's probably not a bug, but a feature.

Memory for quite a number of destructed objects is not immediately freed and given back to the OS, but kept in the pool s for later re-use. The fact that the pools are not freed at the exit of the program cause Valgrind to report this memory as still reachable. The behaviour not to free pools at the exit could be called a bug of the library though. Using GCC, you can force the STL to use malloc and to free memory as soon as possible by globally disabling memory caching.

Doing so will probably slow down your program, sometimes drastically. With GCC 2. This was removed from GCC starting with version 3. With GCC 3. But all this goes beyond the scope of this FAQ. But beware: allocators belong to the more messy parts of the STL and people went to great lengths to make the STL portable across platforms.

Chances are good that your solution will work on your platform, but not on others. If they're not long enough, use --num-callers to make them longer. If they're not detailed enough, make sure you are compiling with -g to add debug information. And don't strip symbol tables programs should be unstripped unless you run 'strip' on them; some libraries ship stripped.

Also, for leak reports involving shared objects, if the shared object is unloaded before the program terminates, Valgrind will discard the debug information and the error message will be full of??? Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search.

First time I used JNI to access a c library and I thought of using valgrind to check for any memory leaks. Valgrind reported so many leaks in jvm. Aside from that it also reports a possible lost in AttachCurrentThread method when in fact I detached it successfully through DetachCurrentThread in my call back function.

Well for me I suspect that the unloading of the library and destroying had not yet been done after my app exits and valgrind already did its checking part. Hope to hear from anyone who had experience this kind of case as well. The JVM and Valgrind don't get along. Just running the JVM under Valgrind with no input for me gives tons of warnings. How are we doing? The suppression mechanism therefore allows you to say which tool or tool s each suppression applies to.

First off, consider whether it might be beneficial to recompile your application and supporting libraries with debugging info enabled the -g option. Without debugging info, the best Valgrind tools will be able to do is guess which function a particular piece of code belongs to, which makes both error messages and profiling output nearly useless. With -g , you'll get messages which point directly to the relevant source code lines. For example, debugging OpenOffice. You don't have to do this, but doing so helps Valgrind produce more accurate and less confusing error reports.

Chances are you're set up like this already, if you intended to debug your program with GNU GDB, or some other debugger. With this, function call chain will be properly shown, even when your application is compiled with inlining. If you are planning to use Memcheck: On rare occasions, compiler optimisations at -O2 and above, and sometimes -O1 have been observed to generate code which fools Memcheck into wrongly reporting uninitialised value errors, or missing uninitialised value errors.

We have looked in detail into fixing this, and unfortunately the result is that doing so would give a further significant slowdown in what is already a slow tool. So the best solution is to turn off optimisation altogether. Since this often makes things unmanageably slow, a reasonable compromise is to use -O.

This gets you the majority of the benefits of higher optimisation levels whilst keeping relatively small the chances of false positives or false negatives from Memcheck. Also, you should compile your code with -Wall because it can identify some or all of the problems that Valgrind can miss at the higher optimisation levels.

Using -Wall is also a good idea in general. All other tools as far as we know are unaffected by optimisation level, and for profiling tools like Cachegrind it is better to compile your program at its normal optimisation level. The reader for "stabs" debugging format used by GCC versions prior to 3.

When you're ready to roll, run Valgrind as described above. Note that you should run the real machine-code executable here. If your application is started by, for example, a shell or Perl script, you'll need to modify it to invoke Valgrind on the real executables. This may not be what you want and can be confusing.

Valgrind tools write a commentary, a stream of text, detailing error reports and other significant events. All lines in the commentary have following form:. The is the process ID. This scheme makes it easy to distinguish program output from Valgrind commentary, and also easy to differentiate commentaries from different processes which have become merged together, for whatever reason.

By default, Valgrind tools write only essential messages to the commentary, so as to avoid flooding you with information of secondary importance. If you want more information about what is happening, re-run, passing the -v option to Valgrind.

A second -v gives yet more detail. The default: send it to a file descriptor, which is by default 2 stderr. So, if you give the core no options, it will write commentary to the standard error stream. There are special format specifiers that can be used to use a process ID or an environment variable name in the log file name.

See the basic options section for more details. The least intrusive option is to send the commentary to a network socket. Writing to a network socket is pointless if you don't have something listening at the other end. We provide a simple listener program, valgrind-listener , which accepts connections on the specified port and copies whatever it is sent to stdout.

Probably someone will tell us this is a horrible security risk. It seems likely that people will write more sophisticated listeners in the fullness of time. In front of each line of output it prints the current number of active connections in round brackets. When the number of connected processes falls back to zero, exit. Without this, it will run forever, that is, until you send it Control-C.

By default, the listener can connect to up to 50 processes. Occasionally, that number is too small. Use this option to provide a different limit. Changes the port it listens on from the default The specified port must be in the range to The same restriction applies to port numbers specified by a --log-socket to Valgrind itself. If a Valgrinded process fails to connect to a listener, for whatever reason the listener isn't running, invalid or unreachable host or port, etc , Valgrind switches back to writing the commentary to stderr.

The same goes for any process which loses an established connection to a listener. In other words, killing the listener doesn't kill the processes sending data to it. Here is an important point about the relationship between the commentary and profiling output from tools. The commentary contains a mix of messages from the Valgrind core and the selected tool. If the tool reports errors, it will report them to the commentary.

The commentary is intended to be a low-bandwidth, human-readable channel. Profiling data, on the other hand, is usually voluminous and not meaningful without further processing, which is why we have chosen this arrangement. When an error-checking tool detects something bad happening in the program, an error message is written to the commentary.

Here's an example from Memcheck:. This message says that the program did an illegal 4-byte read of address 0xBFFFF74C, which, as far as Memcheck can tell, is not a valid stack address, nor corresponds to any current heap blocks or recently freed heap blocks. The read is happening at line 45 of bogon. Valgrind remembers all error reports.

When an error is detected, it is compared against old reports, to see if it is a duplicate. If so, the error is noted, but no further commentary is emitted. This avoids you being swamped with bazillions of duplicate error reports. If you want to know how many times each error occurred, run with the -v option. When execution finishes, all the reports are printed out, along with, and sorted by, their occurrence counts.

This makes it easy to see which errors have occurred most frequently. Errors are reported before the associated operation actually happens. For example, if you're using Memcheck and your program attempts to read from address zero, Memcheck will emit a message to this effect, and your program will then likely die with a segmentation fault.

In general, you should try and fix errors in the order that they are reported. Not doing so can be confusing. For example, a program which copies uninitialised values to several memory locations, and later uses them, will generate several error messages, when run on Memcheck.

The first such error message may well give the most direct clue to the root cause of the problem. The process of detecting duplicate errors is quite an expensive one and can become a significant performance overhead if your program generates huge quantities of errors.

To avoid serious problems, Valgrind will simply stop collecting errors after 1, different errors have been seen, or 10,, errors in total have been seen. In this situation you might as well stop your program and fix it, because Valgrind won't tell you anything else useful after this. Then Valgrind will always show errors, regardless of how many there are.

Use this option carefully, since it may have a bad effect on performance. The error-checking tools detect numerous problems in the system libraries, such as the C library, which come pre-installed with your OS.

You can't easily fix these, but you don't want to see these errors and yes, there are many! So Valgrind reads a list of errors to suppress at startup. A default suppression file is created by the. You can modify and add to the suppressions file at your leisure, or, better, write your own.

Multiple suppression files are allowed. This is useful if part of your project contains errors you can't or don't want to fix, yet you don't want to continuously be reminded of them. This generates suppressions automatically. Each error to be suppressed is described very specifically, to minimise the possibility that a suppression-directive inadvertently suppresses a bunch of similar errors which you did want to see.

The suppression mechanism is designed to allow precise yet flexible specification of errors to suppress. If you use the -v option, at the end of execution, Valgrind prints out one line for each used suppression, giving the number of times it got used, its name and the filename and line number where the suppression is defined.

Depending on the suppression kind, the filename and line number are optionally followed by additional information such as the number of blocks and bytes suppressed by a Memcheck leak suppression.

Multiple suppressions files are allowed. If you want to understand more about suppressions, look at an existing suppressions file whilst reading the following documentation. The file glibc Blank and comment lines in a suppression file are ignored. Comment lines are made of 0 or more blanks followed by a character followed by some text. First line: its name. This merely gives a handy name to the suppression, by which it is referred to in the summary of used suppressions printed out when a program finishes.

It's not important what the name is; any identifying string will do. Second line: name of the tool s that the suppression is for if more than one, comma-separated , and the name of the suppression itself, separated by a colon n. Recall that Valgrind is a modular system, in which different instrumentation tools can observe your program whilst it is running.

Since different tools detect different kinds of errors, it is necessary to say which tool s the suppression is meaningful to. Tools will complain, at startup, if a tool does not understand any suppression directed to it.

Tools ignore suppressions which are not directed to them. As a result, it is quite practical to put suppressions for all tools into the same suppression file.

Next line: a small number of suppression types have extra information after the second line eg. Remaining lines: This is the calling context for the error -- the chain of function calls that led to it.

There can be up to 24 of these lines. Locations may be names of either shared objects, functions, or source lines. They begin with obj: , fun: , or src: respectively. Source lines are specified using the form filename[:lineNumber].

A location line may also be simply " This is a frame-level wildcard, which matches zero or more frames. Frame level wildcards are useful because they make it easy to ignore varying numbers of uninteresting frames in between frames of interest. That is often important when writing suppressions which are intended to be robust against variations in the amount of function inlining done by compilers.

Finally, the entire suppression must be between curly braces. Each brace must be the first character on its own line. A suppression only suppresses an error when the error matches all the details in the suppression. Here's an example:. It doesn't apply under any other circumstances. See Writing suppression files for more details on the specifics of Memcheck's suppression kinds.

This suppresses any size 4 uninitialised-value error which occurs anywhere in libX The inexact specification of locations is regrettable, but is about all you can hope for, given that the X11 libraries shipped on the Linux distro on which this example was made have had their symbol tables removed.

This suppresses any size-4 uninitialised-value error which occurs at line in valid. Although the above two examples do not make this clear, you can freely mix obj: , fun: , and src: lines in a suppression. This suppresses Memcheck memory-leak errors, in the case where the allocation was done by main calling though any number of intermediaries, including zero ccc , calling onwards via ddd and eventually to malloc.

When a debuginfo file cannot be found locally, Valgrind is able to query debuginfod servers for the file using its build-id. These environment variables will be ignored. As mentioned above, Valgrind's core accepts a common set of options.

The tools also accept tool-specific options, which are documented separately for each tool. Valgrind's default settings succeed in giving reasonable behaviour in most cases. We group the available options by rough categories. Run the Valgrind tool called toolname , e. Show help for all options, both for the core and for the selected tool.

If the option is repeated it is equivalent to giving --help-debug. Same as --help , but also lists debugging options which usually are only of use to Valgrind's developers.

Show the version number of the Valgrind core. Tools can have their own version numbers. There is a scheme in place to ensure that tools only execute when the core version is one they are known to work with. This was done to minimise the chances of strange problems arising from tool-vs-core version incompatibilities. Run silently, and only print error messages.

Useful if you are running regression tests or have some other automated test machinery. Be more verbose. Gives extra information on various aspects of your program, such as: the shared objects loaded, the suppressions used, the progress of the instrumentation and execution engines, and warnings about unusual behaviour. Repeating the option increases the verbosity level. When enabled, Valgrind will trace into sub-processes initiated via the exec system call. This is necessary for multi-process programs.

Note that Valgrind does trace into the child of a fork it would be difficult not to, since fork makes an identical copy of a process , so this option is arguably badly named.

However, most children of fork calls immediately call exec anyway. It allows for some children to be skipped. The option takes a comma separated list of patterns for the names of child executables that Valgrind should not trace into. Patterns may include the metacharacters? This can be useful for pruning uninteresting branches from a tree of processes being run on Valgrind. But you should be careful when using it. When Valgrind skips tracing into an executable, it doesn't just skip tracing that executable, it also skips tracing any of that executable's child processes.

In other words, the flag doesn't merely cause tracing to stop at the specified executables -- it skips tracing of entire process subtrees rooted at any of the specified executables. This is the same as --trace-children-skip , with one difference: the decision as to whether to trace into a child process is made by examining the arguments to the child process, rather than the name of its executable. When enabled, Valgrind will not show any debugging or logging output for the child process resulting from a fork call.

This can make the output less confusing although more misleading when dealing with processes that create children. If the embedded gdbserver is enabled but no gdb is currently being used, the vgdb command line utility can send "monitor commands" to Valgrind from a shell. The Valgrind core provides a set of Valgrind monitor commands. A tool can optionally provide tool specific monitor commands, which are documented in the tool specific chapter.

Tools that report errors will wait for " number " errors to be reported before freezing the program and waiting for you to connect with GDB. It follows that a value of zero will cause the gdbserver to be started before your program is executed.

This is typically used to insert GDB breakpoints before execution, and also works with tools that do not report errors, such as Massif. The Valgrind gdbserver will be invoked for each error after --vgdb-error have been reported. You can additionally ask the Valgrind gdbserver to be invoked for other events, specified in one of the following ways:. The values startup exit valgrindabexit respectively indicate to invoke gdbserver before your program is executed, after the last instruction of your program, on Valgrind abnormal exit e.

When enabled, Valgrind will print out a list of open file descriptors on exit or on request, via the gdbserver monitor command v. Along with each file descriptor is printed a stack backtrace of where the file was opened and any details relating to the file descriptor such as the file name or socket details.

Use all to include reporting on stdin , stdout and stderr. When enabled, each message is preceded with an indication of the elapsed wallclock time since startup, expressed as days, hours, minutes, seconds and milliseconds. Specifies that Valgrind should send all of its messages to the specified file descriptor. The default, 2, is the standard error channel stderr. Note that this may interfere with the client's own use of stderr, as Valgrind's output will be interleaved with any output that the client sends to stderr.

Specifies that Valgrind should send all of its messages to the specified file. If the file name is empty, it causes an abort. There are three special format specifiers that can be used in the file name. This is very useful for program that invoke multiple processes. Note: If the program forks and calls exec afterwards, Valgrind output of the child from the period between fork and exec will be lost.

This is useful for processes that produces several files from the same filename template. This specifier is rarely needed, but very useful in certain circumstances eg. If the named environment variable is not set, it causes an abort. If the file name specifies a relative file name, it is put in the program's initial working directory: this is the current directory when the program started its execution after the fork or after the exec. If it specifies an absolute file name ie.

Specifies that Valgrind should send all of its messages to the specified port at the specified IP address. The port may be omitted, in which case port is used. If a connection cannot be made to the specified socket, Valgrind falls back to writing output to the standard error stderr.

This option is intended to be used in conjunction with the valgrind-listener program. For further details, see the commentary in the manual. These options are used by all tools that can report errors, e. Memcheck, but not Cachegrind.

When enabled, the important parts of the output e. Furthermore, the XML output will be sent to a different output channel than the plain text output.