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Sentry Issue: ENGINE-HF

ErrorException: Allowed memory size of 134217728 bytes exhausted (tried to allocate 116526568 bytes)
  File "/lib/elgglib.php", line 947, in fatalErrorShutdownHandler
    \Sentry\captureLastError();
  File "[internal]", line 0

added scoped labels

Example request: https://www.minds.com/fs/v1/thumbnail/1026508015016828928/xlarge

Link to media page: https://www.minds.com/media/1026508015016828928

Offending section of code in /api/v1/thumbnail.php:

            try {
                $finfo = new \finfo(FILEINFO_MIME);
                $contentType = $finfo->buffer($contents) ?: 'image/jpeg';
            } catch (\Exception $e) {
                error_log($e);
                $contentType = 'image/jpeg';
            }

Issue appears related to finfo under PHP 7.3.

Running a referenced test script show the clear performance degradation between our 7.1 and 7.3 builds when calling finfo.

While I'm not able to reproduce the OOM condition in our sandbox, I am able to demonstrate the performance degradation.

PHP 7.1

/var/www/Minds/engine # ITERS=100 php test.php
Took: 0.094574928283691
/var/www/Minds/engine # ITERS=1000 php test.php
Took: 0.91444492340088

PHP 7.3

/var/www/Minds/engine # ITERS=100 php test.php
Took: 0.42086601257324
/var/www/Minds/engine # ITERS=1000 php test.php
Took: 4.215017080307

Likely this is a good place to start looking for the OOM issue.

The referenced performance relates to finfo::file() whereas we are using finfo::buffer().

Using finfo::buffer() does not cause a slow down.

Continuing by instrumenting some mock code to show memory usage before and after finfo::buffer()

There is also the possibility that something prior to this call is using too much memory and this final call tips it over the limit where it would not have done previously.