README.md - external/github.com/maruel/panicparse - Git at Google

 # panicparse

 Parses panic stack traces, densifies and deduplicates goroutines with similar
 stack traces. Helps debugging crashes and deadlocks in heavily parallelized
 process.

 [![PkgGoDev](https://pkg.go.dev/badge/github.com/maruel/panicparse/v2/stack)](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack)
 [![codecov](https://codecov.io/gh/maruel/panicparse/branch/main/graph/badge.svg?token=izj1cLjUi3)](https://codecov.io/gh/maruel/panicparse)
 [![go-recipes](https://raw.githubusercontent.com/nikolaydubina/go-recipes/main/badge.svg?raw=true)](https://github.com/nikolaydubina/go-recipes#-pretty-print-panic-messages)


 panicparse helps make sense of Go crash dumps:

 ![Screencast](https://raw.githubusercontent.com/wiki/maruel/panicparse/parse.gif "Screencast")


 ## Features

    * Race detector support, e.g. it can parse output produced by `go test -race`
    * HTML export.
    * Easy to use as an [HTTP Handler
      middleware](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack#example-package-HttpHandlerMiddleware).
    * High performance parsing.
    * [HTTP web server](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack/webstack#SnapshotHandler)
      that serves a very tight and swell snapshot of your goroutines, much more
      readable than [net/http/pprof](https://pkg.go.dev/net/http/pprof).
    * &gt;50% more compact output than original stack dump yet more readable.
    * 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 any platform supported by Go, including Windows, macOS, linux.
    * Full go module support.
    * Requires >=go1.17. Use v2.3.1 for older Go versions.


 ## Installation

     go install github.com/maruel/panicparse/v2/cmd/pp@latest


 ## Usage

 ### Piping a stack trace from another process

 #### TL;DR

    * Ubuntu (bash v4 or zsh): `|&`
    * macOS, [install bash 4+](README.md#updating-bash-on-macos), then: `|&`
    * Windows _or_ macOS with stock bash v3: `2>&1 |`
    * [Fish](http://fishshell.com/) 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](https://golang.org/src/runtime/panic1.go) via the native [`print()`
 function](https://golang.org/pkg/builtin/#print).


 **Bash v4** or **zsh**: `|&` tells the shell to redirect stderr to stdout,
 it's an alias for `2>&1 |` ([bash
 v4](https://www.gnu.org/software/bash/manual/bash.html#Pipelines),
 [zsh](http://zsh.sourceforge.net/Doc/Release/Shell-Grammar.html#Simple-Commands-_0026-Pipelines)):

     go test -v |&pp


 **Windows or macOS native bash** [(which is
 3.2.57)](http://meta.ath0.com/2012/02/05/apples-great-gpl-purge/): They don't
 have this shortcut, so use the long form:

     go test -v 2>&1 | pp


 **Fish**: `&|` redirects stderr and stdout. It's an alias for `2>&1 |`
 ([fish piping](https://fishshell.com/docs/current/language.html#piping)):

     go test -v &| pp


 **PowerShell**: [It has broken `2>&1` redirection](https://connect.microsoft.com/PowerShell/feedback/details/765551/in-powershell-v3-you-cant-redirect-stderr-to-stdout-without-generating-error-records). 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


 ## Tips

 ### Disable inlining

 The Go toolchain inlines functions when it can. This causes traces to be less
 informative. Optimization also interfere with traces. You can use the following
 to help diagnosing issues:

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

 or

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


 Run `go tool compile -help` to get the full list of valid values for -gcflags.


 ### GOTRACEBACK

 By default, [`GOTRACEBACK`](https://golang.org/pkg/runtime/) defaults to
 `single`, which means that a panic will only return the current goroutine trace
 alone. 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](http://brew.sh) or
 [macports](https://www.macports.org/). 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...
     Done.

 and/or

     /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 install github.com/maruel/panicparse/v2@latest

 then using `panicparse` instead of `pp`:

     go test 2> panicparse

 Hint: You may also use shell aliases

     alias gp=panicparse
     go test 2> gp

     alias p=panicparse
     go test 2> p


 ### webstack in action

 The
 [webstack.SnapshotHandler](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack/webstack#SnapshotHandler)
 http.Handler enables glancing at at a snapshot of your process trivially:

 ![Screencast](https://raw.githubusercontent.com/wiki/maruel/panicparse/panicparse_webstack.gif "Screencast")


 ## Authors

 `panicparse` was created with ❤️️ and passion by [Marc-Antoine
 Ruel](https://github.com/maruel) and
 [friends](https://github.com/maruel/panicparse/graphs/contributors).
	# panicparse

	Parses panic stack traces, densifies and deduplicates goroutines with similar
	stack traces. Helps debugging crashes and deadlocks in heavily parallelized
	process.

	[![PkgGoDev](https://pkg.go.dev/badge/github.com/maruel/panicparse/v2/stack)](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack)
	[![codecov](https://codecov.io/gh/maruel/panicparse/branch/main/graph/badge.svg?token=izj1cLjUi3)](https://codecov.io/gh/maruel/panicparse)
	[![go-recipes](https://raw.githubusercontent.com/nikolaydubina/go-recipes/main/badge.svg?raw=true)](https://github.com/nikolaydubina/go-recipes#-pretty-print-panic-messages)


	panicparse helps make sense of Go crash dumps:

	![Screencast](https://raw.githubusercontent.com/wiki/maruel/panicparse/parse.gif "Screencast")


	## Features

	* Race detector support, e.g. it can parse output produced by `go test -race`
	* HTML export.
	* Easy to use as an [HTTP Handler
	middleware](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack#example-package-HttpHandlerMiddleware).
	* High performance parsing.
	* [HTTP web server](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack/webstack#SnapshotHandler)
	that serves a very tight and swell snapshot of your goroutines, much more
	readable than [net/http/pprof](https://pkg.go.dev/net/http/pprof).
	* >50% more compact output than original stack dump yet more readable.
	* 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 any platform supported by Go, including Windows, macOS, linux.
	* Full go module support.
	* Requires >=go1.17. Use v2.3.1 for older Go versions.


	## Installation

	go install github.com/maruel/panicparse/v2/cmd/pp@latest


	## Usage

	### Piping a stack trace from another process

	#### TL;DR

	* Ubuntu (bash v4 or zsh): `\|&`
	* macOS, [install bash 4+](README.md#updating-bash-on-macos), then: `\|&`
	* Windows _or_ macOS with stock bash v3: `2>&1 \|`
	* [Fish](http://fishshell.com/) 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](https://golang.org/src/runtime/panic1.go) via the native [`print()`
	function](https://golang.org/pkg/builtin/#print).


	Bash v4 or zsh: `\|&` tells the shell to redirect stderr to stdout,
	it's an alias for `2>&1 \|` ([bash
	v4](https://www.gnu.org/software/bash/manual/bash.html#Pipelines),
	[zsh](http://zsh.sourceforge.net/Doc/Release/Shell-Grammar.html#Simple-Commands-_0026-Pipelines)):

	go test -v \|&pp


	Windows or macOS native bash [(which is
	3.2.57)](http://meta.ath0.com/2012/02/05/apples-great-gpl-purge/): They don't
	have this shortcut, so use the long form:

	go test -v 2>&1 \| pp


	Fish: `&\|` redirects stderr and stdout. It's an alias for `2>&1 \|`
	([fish piping](https://fishshell.com/docs/current/language.html#piping)):

	go test -v &\| pp


	PowerShell: [It has broken `2>&1` redirection](https://connect.microsoft.com/PowerShell/feedback/details/765551/in-powershell-v3-you-cant-redirect-stderr-to-stdout-without-generating-error-records). 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


	## Tips

	### Disable inlining

	The Go toolchain inlines functions when it can. This causes traces to be less
	informative. Optimization also interfere with traces. You can use the following
	to help diagnosing issues:

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

	or

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


	Run `go tool compile -help` to get the full list of valid values for -gcflags.


	### GOTRACEBACK

	By default, [`GOTRACEBACK`](https://golang.org/pkg/runtime/) defaults to
	`single`, which means that a panic will only return the current goroutine trace
	alone. 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](http://brew.sh) or
	[macports](https://www.macports.org/). 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...
	Done.

	and/or

	/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 install github.com/maruel/panicparse/v2@latest

	then using `panicparse` instead of `pp`:

	go test 2> panicparse

	Hint: You may also use shell aliases

	alias gp=panicparse
	go test 2> gp

	alias p=panicparse
	go test 2> p


	### webstack in action

	The
	[webstack.SnapshotHandler](https://pkg.go.dev/github.com/maruel/panicparse/v2/stack/webstack#SnapshotHandler)
	http.Handler enables glancing at at a snapshot of your process trivially:

	![Screencast](https://raw.githubusercontent.com/wiki/maruel/panicparse/panicparse_webstack.gif "Screencast")


	## Authors

	`panicparse` was created with ❤️️ and passion by [Marc-Antoine
	Ruel](https://github.com/maruel) and
	[friends](https://github.com/maruel/panicparse/graphs/contributors).