Linux process state while waiting for a HTTP response
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In Linux, what happens to the state of a process (curl, postman, mule, caml) when it has sent a HTTP request and waiting for a HTTP response? What is the way to know how long the process is waiting for the response?
Depends on what exactly generated that request. For example, if you
are developing in Angular or hosting an Angular app on Linux, any http
request is asynchronous and can take several seconds for the data to
show up. Angular deals with this by making promises and then filling
them when the data is returned. Royal PITA to deal with. In Java, some
http request libraries are synchronous, some are asynchronous. PHP,
cURL, etc. are all synchronous. So... It Depends?
Still applies. Have headers been sent, but waiting on data transmission to start? Waiting on headers? Half the data has been sent but there is a temporary transmission pause?
Anyway, curl reports as "sleeping", didn't want to deal with writing more code and experimenting for the others. Perhaps some method of relating voluntary context switches to elapsed time would work?
With curl, and a simple script -
<?php
sleep(60);
print("done");
?>
a curl http://localhost/wait.php shows in /proc/PID/status that it is sleeping. No indicator of time that I can see - here's the output, note I had to start the curl, click to change focus, etc. so more than a few seconds into it
user@darkstar:~ $ /usr/bin/time -v curl http://localhost/wait.php
Done Command being timed: "curl http://localhost/wait.php"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 0%
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:00.01
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 7596
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 403
Voluntary context switches: 63
Involuntary context switches: 2
Swaps: 0
File system inputs: 0
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0
After the update to the question, my comment of -
Still applies. Have headers been sent, but waiting on data transmission to start? Waiting on headers? Half the data has been sent but there is a temporary transmission pause?
Anyway,
curlreports as "sleeping", didn't want to deal with writing more code and experimenting for the others. Perhaps some method of relating voluntary context switches to elapsed time would work?With
curl, and a simple script -a
curl http://localhost/wait.phpshows in/proc/PID/statusthat it is sleeping. No indicator of time that I can see - here's the output, note I had to start the curl, click to change focus, etc. so more than a few seconds into itAnd a (better)
timecommand run -