How to spy on a Ruby program

#1

Post by bartbes » Sun, Jun 12, 2016, 10:29 AM UTC

How to spy on a Ruby program
jvns.ca

Re: How to spy on a Ruby program

#2

Post by nxzero » Sun, Jun 12, 2016, 11:36 AM UTC

One issue I've run across is spying on JRuby's native Java classes. Anyone have a solution?

Re: How to spy on a Ruby program

#3

Post by ch4s3 » Sun, Jun 12, 2016, 1:22 PM UTC

nxzero wrote: post #2

One issue I've run across is spying on JRuby's native Java classes. Anyone have a solution?

I've only ever used VirtualVM, maybe Charles Nutter or Chris Seaton will appear and enlighten us both.

Re: How to spy on a Ruby program

#4

Post by guptaneil » Sun, Jun 12, 2016, 1:47 PM UTC

> maybe it doesn't exist because a Linux-only Ruby debugging tool is sort of a weird thing?

Linux-only seems perfectly acceptable, especially as more and more development moves to Docker containers.

Great write up, looking forward to seeing a completed tool!

Re: How to spy on a Ruby program

#5

Post by chrisseaton » Sun, Jun 12, 2016, 1:48 PM UTC

ch4s3 wrote: post #3

nxzero wrote: post #2

One issue I've run across is spying on JRuby's native Java classes. Anyone have a solution?

I've only ever used VirtualVM, maybe Charles Nutter or Chris Seaton will appear and enlighten us both.

I'm not sure what you want to do. Is your problem that you do want to see the native Java classes, or you want to hide them and focus on the Ruby code? Or is the key thing you want a Java flame graph?

Re: How to spy on a Ruby program

#6

Post by eeZi » Sun, Jun 12, 2016, 1:49 PM UTC

For Python, you can just use Pyrasite (https://github.com/lmacken/pyrasite) and inject a script which prints a stack trace for all threads.

I've done this to debug OpenStack in the past and it worked very well. There are many similar projects for Python, I used this one since it's in the RHEL repo.

Useful summary on StackOverflow: https://stackoverflow.com/questions/4163964/python-is-it-pos...

Re: How to spy on a Ruby program

#7

Post by camperman » Sun, Jun 12, 2016, 1:50 PM UTC

I hadn't heard of perf - very handy indeed. It's in the linux-tools package for distros using apt. You will need to install both the generic package and the one for your kernel version.

Re: How to spy on a Ruby program

#8

Post by eeZi » Sun, Jun 12, 2016, 1:51 PM UTC

guptaneil wrote: post #4

> maybe it doesn't exist because a Linux-only Ruby debugging tool is sort of a weird thing? Linux-only seems perfectly acceptable, especially as more and more development moves to Docker containers. Great write up, looking forward to seeing a completed tool!

Windows Docker is just around the corner!

Re: How to spy on a Ruby program

#9

Post by ch4s3 » Sun, Jun 12, 2016, 1:57 PM UTC

chrisseaton wrote: post #5

ch4s3 wrote: post #3

Earlier quoted context omitted.

I've only ever used VirtualVM, maybe Charles Nutter or Chris Seaton will appear and enlighten us both.

I'm not sure what you want to do. Is your problem that you do want to see the native Java classes, or you want to hide them and focus on the Ruby code? Or is the key thing you want a Java flame graph?

Java classes and a flame graph would be nice sometimes. I really only know how to use pry and Virtual VM with JRuby.

Re: How to spy on a Ruby program

#10

Post by ch4s3 » Sun, Jun 12, 2016, 1:58 PM UTC

chrisseaton wrote: post #5

ch4s3 wrote: post #3

Earlier quoted context omitted.

I've only ever used VirtualVM, maybe Charles Nutter or Chris Seaton will appear and enlighten us both.

I'm not sure what you want to do. Is your problem that you do want to see the native Java classes, or you want to hide them and focus on the Ruby code? Or is the key thing you want a Java flame graph?

Interesting, it looks like Sam Saffron's FlameGraph gem https://github.com/SamSaffron/flamegraph has worked with JRuby for about a year and I hadn't noticed.