log_errors_max_len = 1024 in php.ini, but php log keeps growing

Question

As the title says, I\'ve set the max length for the php error log, but it seems to keep growing much much larger than 1024. I am using the correct php.ini, I\'ve restarted

Answer 1

What the manual doesn't state is that log_errors_max_len refers only to the "body" of the error message. This means that a single line of error will still be greater than the length you set here.

To demonstrate, run this code using log_errors_max_len=0 (0 means unlimited) and log_errors=1:

The bytes sent to error_log will be:

[15-Jul-2015 01:23:45 utc] PHP Notice:  Undefined variable: msg1 in C:\index.php on line 5
[15-Jul-2015 01:23:45 utc] PHP Notice:  Undefined variable: msg2 in C:\index.php on line 5
‏

Next, test the same code with log_errors_max_len=4 and log_errors=1. (Remember to restart the server.) error_log will now be:

[15-Jul-2015 01:23:45 utc] PHP Notice:  Unde in C:\index.php on line 5
[15-Jul-2015 01:23:45 utc] PHP Notice:  Unde in C:\index.php on line 5
‏

(Notice that your error message is prepended with "[15-Jul-2015 01:23:45 utc] PHP Notice:" and appended with "in C:\index.php on line 1", resulting in a line longer than what is set by log_errors_max_len.)

This issue occurs not just with error_log, but also with the server output sent to the client. To demonstrate, run the same code above using log_errors_max_len=4, display_errors=1, html_errors=0, error_prepend_string="PPPP", and error_append_string="AAAA". The output sent to the client is:

PPPP
Notice: Unde in C:\index.php on line 5
AAAAPPPP
Notice: Unde in C:\index.php on line 5
AAAA

Now run the same code using log_errors_max_len=4, display_errors=1, html_errors=1, error_prepend_string="PPPP", and error_append_string="AAAA". (error_prepend_string and error_append_string apply only to displayed errors, not logged errors.) The output sent to the client is:

PPPP

Notice:  Unde in C:\index.php on line 5

AAAAPPPP

Notice:  Unde in C:\index.php on line 5

AAAA

Also note that the above tests would return the same results even if you use ignore_repeated_errors=0. This shows that "repeated errors" are considered before the error messages are cropped.

(Your results may differ depending on the SAPI used. Above tests are done using php-5.6.7-Win32-VC11-x86 CLI on win 8.1.)