Add PHP support about pyroscope HOT 10 CLOSED

I would like to help with this but am not sure where to start. I'm thinking we could leverage some of the existing sampling profilers out there but am not sure what changes need to be made to their output for Pyroscope to read them correctly.

Examples,

• https://github.com/adsr/phpspy
• https://github.com/sj-i/php-profiler
• https://github.com/nikic/sample_prof

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@markhuot This is already very useful! phpspy looks very promising. Profilers we use for python and ruby (py-spy and rbspy) use a similar approach for getting the profiling data (they look at process memory X number of times per second) and I bet it would be relatively straightforward to add phpspy to pyroscope if we modify it just a little bit.

For example, here's how we integrated rbspy into pyroscope:

• we modified rbspy to compile into a library instead of an executable binary
• we modified rbspy code to implement the following interface: https://github.com/pyroscope-io/rbspy/blob/main/lib/rbspy.h#L3-L5
• once you can build a static library that complies with this interface, integrating it with go is pretty straightforward: https://github.com/pyroscope-io/pyroscope/blob/main/pkg/agent/rbspy/rbspy.go#L1-L74

C Interface

The C interface has 3 functions, they all take a PID and a buffer to report errors to. snapshot function also takes a buffer that it writes the stack-trace to.

rbspy_init initializes the spy

int rbspy_init(pid_t pid, void* err_ptr, int err_len);

rbspy_cleanup releases the resources associated with the initialization

int rbspy_cleanup(pid_t pid, void* err_ptr, int err_len);

rbspy_snapshot is the most important one, it copies the current stack trace of the process to ptr

int rbspy_snapshot(pid_t pid, void* ptr, int len, void* err_ptr, int err_len);

I hope this is enough information to get started. @markhuot Ping me in our Slack, I would love to help, this seems very promising.

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Thanks for these pointers @petethepig! I've dug in to phpspy and have a much better understanding of how it's working and what it's doing now. Unfortunately the C work is a bit outside my day-to-day experience so I'm getting up to speed on that. In your first bullet you say "we modified rbspy to compile into a library instead of an executable binary." Is that something you did inside the rbspy logic or a flag you flip on the compiler?

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Ah, I think I see. I've been looking through this commit for inspiration, grafana/rbspy@00dbbe4

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@markhuot I think for a C library it will be more of a flag in the compiler type thing.

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PHP support would be really useful.

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Started working on it in #157

@markhuot — I set up all the C library scaffolding, I think all that's left to do is connecting the profiling code to the interface.

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Also made this diagram describing the relationship between components:

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@adrianandreias @arrack @jamesaspence @jnlin @kcloze @knibals @Kortivex @markhuot @Slach @tooolbox @topazas @vearutop

We've just released v0.0.31 with php support. Please try it out, we would love to hear feedback from any of you.

Currently it only works on Linux and the way to start it is by using pyroscope exec:

pyroscope exec php main.php

Or you can also connect to an existing php process:

pyroscope connect -pid <pid of the process>

We also have a dockerized example project here

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Closing this, PHP support is already provided through phpspy.

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