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Crash your app in style (Golang)

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Statistics on panicparse

Number of watchers on Github 2284
Number of open issues 8
Average time to close an issue about 2 months
Main language Go
Average time to merge a PR 1 day
Open pull requests 2+
Closed pull requests 10+
Last commit 2 months ago
Repo Created over 5 years ago
Repo Last Updated 20 days ago
Size 2.14 MB
Homepage https://maruel.ca
Organization / Authormaruel
Latest Releasev1.5.0
Page Updated
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Parses panic stack traces, densifies and deduplicates goroutines with similar stack traces. Helps debugging crashes and deadlocks in heavily parallelized process.

GoDoc Go Report Card Coverage Status Build Status

panicparse helps make sense of Go crash dumps:



  • New in v2.0.0!: Completely refactored stack package for higher performance.
  • New in v1.4.0!: webstack.SnapshotHandler is a http handler that serves a very tight and swell snapshot of your goroutines, much more readable than net/http/pprof.
  • >50% more compact output than original stack dump yet more readable.
  • Exported symbols are bold, private symbols are darker.
  • Stdlib is green, main is yellow, rest is red.
  • Deduplicates redundant goroutine stacks. Useful for large server crashes.
  • Arguments as pointer IDs instead of raw pointer values.
  • Pushes stdlib-only stacks at the bottom to help focus on important code.
  • Parses the source files if available to augment the output.
  • Works on Windows.

webstack in action



panicparse was created with and passion by Marc-Antoine Ruel and friends.


go get github.com/maruel/panicparse/cmd/pp


Piping a stack trace from another process


  • Ubuntu (bash v4 or zsh): |&
  • macOS, install bash 4+, then: |&
  • Windows or macOS with stock bash v3: 2>&1 |
  • Fish shell: ^|

Longer version

pp streams its stdin to stdout as long as it doesn't detect any panic. panic() and Go's native deadlock detector print to stderr via the native print() function.

Bash v4 or zsh: |& tells the shell to redirect stderr to stdout, it's an alias for 2>&1 | (bash v4, zsh):

go test -v |&pp

Windows or macOS native bash (which is 3.2.57): They don't have this shortcut, so use the long form:

go test -v 2>&1 | pp

Fish: It uses ^ for stderr redirection so the shortcut is ^|:

go test -v ^|pp

PowerShell: It has broken 2>&1 redirection. The workaround is to shell out to cmd.exe. :(

Investigate deadlock

On POSIX, use Ctrl-\ to send SIGQUIT to your process, pp will ignore the signal and will parse the stack trace.

Parsing from a file

To dump to a file then parse, pass the file path of a stack trace

go test 2> stack.txt
pp stack.txt


Disable inlining

Starting with go1.11, the toolchain starts to inline more often. This causes traces to be less informative. You can use the following to help diagnosing issues:

go install -gcflags '-l' path/to/foo
foo |& pp


go test -gcflags '-l' ./... |& pp


Starting with Go 1.6, GOTRACEBACK defaults to single instead of all / 1 that was used in 1.5 and before. To get all goroutines trace and not just the crashing one, set the environment variable:

export GOTRACEBACK=all

or set GOTRACEBACK=all on Windows. Probably worth to put it in your .bashrc.

Updating bash on macOS

Install bash v4+ on macOS via homebrew or macports. Your future self will appreciate having done that.

If you have /usr/bin/pp installed

If you try pp for the first time and you get:

Creating tables and indexes...


/usr/bin/pp5.18: No input files specified

you may be running the Perl PAR Packager instead of panicparse.

You have two choices, either you put $GOPATH/bin at the beginning of $PATH or use long name panicparse with:

go get github.com/maruel/panicparse

then using panicparse instead of pp:

go test 2> panicparse
panicparse open issues Ask a question     (View All Issues)
  • about 4 years [feature] mark stdlib entries distinctively
  • about 4 years [feature] "vim/compiler-like format" [-format=vim? =quickfix?]
  • about 4 years [feature] --only: show only the stacktrace lines, filter out the rest
  • about 4 years [feature] rank "unique snowflakes" higher
  • over 5 years convert stack/stack.go to a formal state machine
panicparse open pull requests (View All Pulls)
  • basic filter implementation
  • allow matching and filtering traces
panicparse list of languages used
panicparse latest release notes
v2.0.0-alpha1 Initial v2 release
  • Enabled race detector parsing!
  • Significantly accelerated performance for pass through.
  • Significant refactoring of the package stack.
  • Removed vendor/ since it's not used anymore by current Go versions. As such, the minimum required version is now 1.9.x.
  • Includes recent v1.5.0 go module support.
v1.5.0 Fixed out-of-GOPATH parsing

Lots of nice things before v2:

  • Add support for local go module outside of GOPATH. It only works well if remote and local paths match.
  • Fix panicweb on macOS.
  • Wrap errors where applicable on go 1.13 and later.
  • Ran staticcheck and fixed all warnings.
  • Fixed tests on 32 bits when -race is not supported.
  • Many internal refactoring in preparation for v2.
v1.4.1 Lower IsPtr floor to 4MiB; slightly faster

Most of the changes are test-only changes to help in preparation for v2.

The only user visible changes are IsPtr floor was lowered from 8MiB to 4MiB and processing is now a bit faster and more memory efficient.

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