comment on

If you give us more information we should be able to help. Meanwhile, these old nodes might give you a clue as to what your problem might be.

Using this node for Memory Tools References nowadays:

Re^2: Perl, C and deallocation responsibility (Returning Memory back to the OS References) - Perl on Linux and Windows (unlike most other Perl platforms) does return "big" chunks of memory back to the OS

General Areas to consider when faced with a Memory Leak

Stability: Once your process grows to a certain size, does it stay there, or does it grow further over time?
Large CPAN Modules. Are you using any?
Circular references. See Eliminate circular reference memory leak using weaken (Perl Maven).
Scoping.
File/Database handling.
Tools. Try one or more from the following section.

Perl Tools and Advice

Profiling Memory Usage talk by Tim Bunce (YAPC::NA Austin Texas 2013 featuring Devel::SizeMe). Resident size vs vm size, rss, segments, /proc/pid/maps (e.g. SO maps question), malloc and the heap, perl internals, pads, constant folding, arenas, recursion, perl data structures (lots of pointers), ... (update: this reply describes memory used by lexical variables in subroutines at the 09:20 minute mark)
Plans for adding memory profiling to Devel::NYTProf
Devel::NYTProf
Devel::Gladiator
Devel::LeakTrace
Test::LeakTrace
Devel::Leak
Devel::FindRef
Devel::Cycle
Test::Memory::Cycle
Devel::MemoryTrace::Light

Devel::SizeMe by Tim Bunce (mentioned in talk above)
Devel::Size
Devel::DumpSizes
Devel::Arena
Devel::Mallinfo
Devel::Peek

splain (diagnostics, splain - produce verbose warning diagnostics)
perldiag (search for "out of memory", "malloc", etc)
perlvar (search for "$^M")
perlfaq3 (search for "malloc", "memory", ..., perl -V:usemymalloc displays value of "usemymalloc" configuration variable)
How can I free an array or hash so my program shrinks? (perlfaq3)
How can I make my Perl program take less memory? (perlfaq3)

INSTALL (Build and Installation guide for perl 5, ... search for malloc)
perl malloc.c source code

Perl::Critic - static code analysis for Perl
MCE::Shared

Mini-Tutorial: Perl's Memory Management by ikegami
As pointed out by dave_the_m: "once the perl interpreter has exhausted all memory, there's very little it can do. There is a reserved fixed buffer to allow it to display the OOM error itself, but doing anything complex like displaying a Carp::confess()-like stack backtrace would require many memory allocations to generate the display, all of which would themselves fail".

General Tools

Memory leak (wikipedia)
Memory debugger (wikipedia - contains a list of memory debugging tools)
Top 20 list of memory leak detection tools (softwaretestinghelp)
Valgrind (see also: Test::Valgrind mentioned here)
AddressSanitizer (wikipedia)
VTune memory profiler (wikipedia) - a performance analysis tool for x86 based machines running Linux or Microsoft Windows operating systems

Clang (Clang is a compiler front end for the C, C++, Objective-C, and Objective-C++ programming languages ... includes a static analyzer, and several code analysis tools ... Clang operates in tandem with the LLVM compiler back end)
LLVM (LLVM is a set of compiler and toolchain technologies that can be used to develop a front end for any programming language and a back end for any instruction set architecture ... designed around a language-independent intermediate representation (IR) that serves as a portable, high-level assembly language that can be optimized with a variety of transformations over multiple passes)
Boehm garbage collector aka Boehm–Demers–Weiser garbage collector (wikipedia)

Static Code Analysis

Static code analysis (wikipedia)
List of tools for static code analysis (wikipedia)
CodeSonar static code analysis (wikipedia)
Coverity static code analysis (wikipedia)
Dynamic program analysis (wikipedia)

Duplicate code (wikipedia)
DRY (wikipedia)
Rule of three (wikipedia)

Code Profiling and Optimization

Re: declaring lexical variables in shortest scope: performance? (on Code Optimization and Performance References)

Testing Concurrent Software

Re: Threads or no Threads (Threading, Forking, Signals, Event Loop and Concurrency References)

Security Testing

Re: Security techniques every programmer should know (Security References) (long list of Security references)

Some Related PM Nodes

Is $^M a leftover April Fool? by BrowserUk (2003)
How use $^M? by xiaoyafeng (2021)
Make Perl use real malloc by creamygoodness (2011)

Re^2: Do subroutine variables get destroyed? (Deterministic Destructor References) (discusses deterministic destructors, tracing vs reference-counted garbage collectors, RAII, ...)
Re^2: A short whishlist of Perl5 improvements leaping to Perl7 (compares Perl's simple lexical scoping with Python's global and nonlocal keywords)

More Nodes Added Later

Small Hash a Gateway to Large Hash? by lsherwood (2014)
write hash to disk after memory limit by hailholyghost (2015)
Do subroutine variables get destroyed? by bt101 (2016)
Perl and Garbage Collection by Svetlana (2016)

Perl "Out of memory!" Error signal backtrace by OnEhIppY (2021)
Memory efficient design by harangzsolt33 (2022)
Memory usage double expected by sectokia (2022)

Re: FFI::Platypus: Replace malloc with GC_MALLOC? by ikegami (2022)
Re^3: FFI::Platypus: Replace malloc with GC_MALLOC? by me (2022)
Perl, C and deallocation responsibility by SheWolf (2023)
Re^2: Perl, C and deallocation responsibility (Returning Memory back to the OS References) by me (2023)
Re: Tk-804.036 build failure by syphilis (2023) - 32-bit build ok, 64-bit build crashes (also gcc v clang)

Re^3: Extracting selected fields form file record (don't use File::Slurp References) by me (2023) - see haukex reply
Does Perl have a baked-in memory llimit? by cormanaz (2023) - out of memory File::Slurp-ing a half-gig file, with 32 GB of system memory (32 v 64 bit perl build?)
Memory limitation of a perl process in Unix by asinghvi (2004) - out of memory: is there a memory limit on a perl process on Unix/Solaris?
Re^5: Is there something faster than string concatenation? (hermit crabs) by me (2007) - performance of Perl string concatenation depends on performance of the underlying C library realloc function

Strawberry: Both IO and global match are VERY SLOW. Unless pre-heated (but why?) by anonymonk (2023) - see replies by syphilis, Discipulus and tonyc

Recursion

Profiling Memory Usage talk by Tim Bunce (YAPC::NA Austin Texas 2013 featuring Devel::SizeMe). Resident size vs vm size, rss, segments, /proc/pid/maps (e.g. SO maps question), malloc and the heap, perl internals, pads, constant folding, arenas, recursion, perl data structures (lots of pointers), ... (update: this reply describes memory used by lexical variables in subroutines at the 09:20 minute mark)
Re^2: Perl Deep Recursion locks up modern linuxes? by me (2016)
Re^3: Memory usage double expected (run-time) by me (2022)
Re^3: How am i doing? by harangzsolt33 (2025) - "If it's a recursion, it needs to be written as a for loop or some kind of loop. If you see that your sub-routine calls itself, double check that. That's often a program design error" - this nonsense provoked many useful replies. :)

See Also

Updated: Many extra references were added long after the original reply was made.

In reply to Re: Perl Memory problem ... (Memory Tools References) by eyepopslikeamosquito
in thread Perl Memory problem ... by Sascha2018

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