Hi +elspuddo thanks for this demo. It did educate me a little bit on the mental process of reading an strace capture file. It's something I have been trying to learn for years. This was useful. I need to see more of these though. Thanks!
Very helpful, although I ended up greping for my IP address rather than the PID but left me with a problem ... strace'ing the php script I'm troubleshooting shows the script outputs to the console in around 0.02 seconds ... but all the test I run over the internet show a TTFB of around 0.8 to 0.9 seconds - I've ruled out the network (pings are sub 20ms) and the server load average is very low - any ideas of how to troubleshoot this further?
If i understand well at 3:42, if we didn't have dual stack and IPv6 support we would be unable to find the corresponding httpd PID? strange! It is only possible to do that by pushing the Timeout of Apache. in httpd.conf you can put Timeout 8000 & RequestReadTimeout Header=8000 Body=8000
you can specify the file to cut instead of using cat and redirecting the output (and by using tail instead of head I don't have to type that one extra 'r': cut -c12-16 /tmp/output | sort -n | tail very cool demo though - I'd no idea about the -s argument that strace has - thank you!
Glad you liked it! It's amazing that folks are still getting something out of a 10 year old video. I continue to employ the "useless use of a cat" paradigm simply because I like pipes, and I find the explicit cat satisfying.
@@masterchief1520 It's mostly a mix of reading and then trying to put what I've read into practice. I understand things a lot better after I try to use that knowledge for something practical. Writing about a topic in order to explain it to someone else is also super helpful for gaining a better understanding. This helps reveal things that you might have glossed over and only have a superficial understanding of.
Top quality demonstration. Thank You!
Hi +elspuddo thanks for this demo. It did educate me a little bit on the mental process of reading an strace capture file. It's something I have been trying to learn for years. This was useful. I need to see more of these though. Thanks!
Awesome demo, thanks! What's the font? Where can I download the background image from?
I'll have to apply this to Apache and Perl now. Good job on the video and thanks.
very thorough and "extreme" web debugging. Might come in handy one day.
Very informative - never used strace before so I learned a lot!
Yes, so glad you're making more...
Very helpful, although I ended up greping for my IP address rather than the PID but left me with a problem ... strace'ing the php script I'm troubleshooting shows the script outputs to the console in around 0.02 seconds ... but all the test I run over the internet show a TTFB of around 0.8 to 0.9 seconds - I've ruled out the network (pings are sub 20ms) and the server load average is very low - any ideas of how to troubleshoot this further?
I really enjoy viewing this video!
Damn this is interesting, I'm going to watch this later when I understand these topics better (especially Unix networking stuff).
Did you bump up the Apache timeouts? IIRC you dont typically get that long to look for it.
Cool, at 11:00 you just confirmed why my FOG servers interface without internet is slow-ish: DNS.
Simply awesome video!
I wonder if its possible to use STRACE to see if a process is trying to delete files/folders...
If i understand well at 3:42, if we didn't have dual stack and IPv6 support we would be unable to find the corresponding httpd PID? strange! It is only possible to do that by pushing the Timeout of Apache. in httpd.conf you can put Timeout 8000 & RequestReadTimeout Header=8000 Body=8000
Great and informative video, many thanks for your effort!
What are you using as your terminal? I'd love to know what you did to rename your open windows and scroll through them in a list.
man screen :)
That's not the terminal doing that, it's GNU Screen.
Does this not work with php-fpm and per site pools? I get the http worker pid but it doesn't match up to any actual pids on the system
sort -k2 -rn /tmp/output | head :) saved TWO kittehs!
This is amazing! Thanks for sharing it!
This was very useful, thank you.
video is very informative. please turn your volume up though :)
Amazing explanation! My respect o/
you can specify the file to cut instead of using cat and redirecting the output (and by using tail instead of head I don't have to type that one extra 'r':
cut -c12-16 /tmp/output | sort -n | tail
very cool demo though - I'd no idea about the -s argument that strace has - thank you!
Glad you liked it! It's amazing that folks are still getting something out of a 10 year old video. I continue to employ the "useless use of a cat" paradigm simply because I like pipes, and I find the explicit cat satisfying.
@@elspuddo How do you deep dive into concepts? What's your process in understanding stuff?
@@masterchief1520 It's mostly a mix of reading and then trying to put what I've read into practice. I understand things a lot better after I try to use that knowledge for something practical. Writing about a topic in order to explain it to someone else is also super helpful for gaining a better understanding. This helps reveal things that you might have glossed over and only have a superficial understanding of.
awesome. thank you sir!
Why doesn't this command work for me lsof -p `pidof telnet`? I'm use Debian Wheezy.
Does your system have the "pidof" command? You can usually check by running which pidof
top notch! thank you very much!
Is it possible to strace all the processes for a specific call?
Simply ... Amaaaaaaaazing ^____^
Excellent!
suuuubscribed... very awesome demo.. thanks!
Any reason why this command doesn't work on my machine?
root@master:~# lsof -p `pidof telnet`
lsof: no process ID specified
lsof 4.81
Excellent technique. Sadly I'm still a vi holdout.