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IDProjectCategoryView StatusLast Update
0002062XdebugDocumentationpublic2022-12-08 18:50
Reportervijayan Assigned Toderick  
Status closedResolutionfixed 
PlatformLinuxOSUbuntuOS Version21.10 (impish)
Product Version3.0.3 
Fixed in Version3.2.0 
Summary0002062: Profiler can't able to write cachegrind file at /tmp

The reason is the system unit is set to true for the config PrivateTmp which results in profile cachegrind file not generated and no error at all in xdebug.log which leads to confusion. I know this is not controlled by xdebug shared object binary. What I'm planned to suggest is adding a hint or few lines about PrivateTmp may be the reason even you set mode bits to 1777 for /tmp directory but the profiler not writing the cachegrind therefore change the output directory to somewhere where you can provide write permission to apache user.

Additional Information

For further reading about PrivateTmp:

TagsNo tags attached.
Operating SystemLinux
PHP Version8.0.10-8.0.19



2022-02-21 10:05

administrator   ~0006204

If the system is configured with PrivateTmp, then when Xdebug writes to "/tmp", it is actually redirected to the configured PrivateTmp directory. Because it can write there, you won't get any warnings. Unfortunately when I checked in the past to see how I can find that PrivateTmp is enabled, I found no way to do so. Otherwise I would have added such a warning already.

However, I don't think the issue here is "Profiler can't write cachegrind file", but rather that it shows up in a directory that you didn't expect. Can you confirm that?


2022-02-21 12:14

reporter   ~0006207

Yes, you're correct. I expected it have to be at "/tmp" but found the cachegrind file at private temp directory like "/tmp//systemd-private-6ff598b83ece420295c55c310ace4e20-apache2.service-a8yDRu/tmp/cachegrind.out.31644". But when I invoke the function "xdebug_info()" it shows the wrong path as in the attached image. So adding extra information about this would be helpful.


2022-03-02 13:54

administrator   ~0006224

I agree, but so far I have not yet found a way on how to detect this, and give you the right file name there. From the PHP process (and hence Xdebug's) point of view, the file is written to /tmp, it's just that the OS sneakily has changed what /tmp meant to some private tmp directory.


2022-03-04 11:07

administrator   ~0006227

I've made a PR to warn when/if this happens:


2022-03-04 14:15

administrator   ~0006228

Fixed for Xdebug 3.2.0 (coming out in a few months). Please try GitHub's latest from the master branch, if you want to try it out!


2022-03-04 14:35

reporter   ~0006229

Thanks for your help and the clarification. Will try Xdebug 3.2.0 sooner.

Issue History

Date Modified Username Field Change
2022-02-17 12:06 vijayan New Issue
2022-02-21 10:05 derick Assigned To => derick
2022-02-21 10:05 derick Status new => feedback
2022-02-21 10:05 derick Note Added: 0006204
2022-02-21 12:14 vijayan Note Added: 0006207
2022-02-21 12:14 vijayan File Added: Screenshot from 2022-02-21 17-41-07.png
2022-02-21 12:14 vijayan Status feedback => assigned
2022-03-02 13:54 derick Note Added: 0006224
2022-03-02 14:11 derick Status assigned => confirmed
2022-03-04 11:07 derick Status confirmed => assigned
2022-03-04 11:07 derick Note Added: 0006227
2022-03-04 14:15 derick Status assigned => closed
2022-03-04 14:15 derick Resolution open => fixed
2022-03-04 14:15 derick Fixed in Version => 3.2dev
2022-03-04 14:15 derick Note Added: 0006228
2022-03-04 14:35 vijayan Note Added: 0006229
2022-07-20 15:49 derick Fixed in Version 3.2dev => 3.2.0alpha1
2022-12-08 18:50 derick Fixed in Version 3.2.0alpha1 => 3.2.0