Bug #80376 [Opn]: last day of the month causes runway cpu usage

Edit report at https://bugs.php.net/bug.php?id=80376&edit=1 ID: 80376 User updated by: mav2287 at aol dot com Reported by: mav2287 at aol dot com Summary: last day of the month causes runway cpu usage Status: Open Type: Bug Package: Date/time related Operating System: OS X 10.11.6 El Capitan PHP Version: 7.4.12 Block user comment: N Private report: N New Comment: I was able to get GDB installed and I was able to get both 7.3 and 7.4 re-compiled with --enable-debug so that I could use GDB. That is when things got interesting or annoying depending on how you look at it. The bug was not present and I couldn't replicate it after compiling with --enable-debug as a sanity check I compiled both again with it and sure enough the bug was back. Any ideas how to get a backtrace since the bug doesn't show up when the --enable-debug flag is set? Previous Comments: ------------------------------------------------------------------------ [2020-11-22 05:55:54] requinix@php.net No. Xdebug provides a backtrace of PHP code, but what we need here is a backtrace of PHP's own internals. I don't know Macs well, but if you can install gdb then using it is pretty simple: 1. Put the PHP code into a file so you can execute it more easily 2. Start gdb by telling it to load PHP (as in the program) 3. Have it run PHP, passing an argument of the file name so PHP will run the file 4. Let it run for a couple seconds so that it's definitely hung somewhere 5. Interrupt PHP with... Cmd+C? Or maybe Ctrl+C. 6. Have gdb create a backtrace with the bt command Basically, your terminal window will probably end up looking something like > gdb /path/to/php (gdb loads) > (gdb) run /path/to/file.php (no output while php hangs) Cmd+C > (gdb) bt (backtrace output) Take a look at the output, see if it appears like it might be useful, and post it. Ideally you would use a debug build of PHP for this, which includes more information than regular builds do, but with some luck that won't be necessary. For bonus points, repeat that process a few times, and compare the backtraces to see what is and isn't common between them. ------------------------------------------------------------------------ [2020-11-22 01:57:08] mav2287 at aol dot com Haven't done a debug backtrace like that before and don't have gdb on that system is this something I can do with Xdebug? ------------------------------------------------------------------------ [2020-11-17 21:30:44] requinix@php.net Unless someone else can reproduce this (I couldn't on Linux), Can you try running PHP with gdb or another debugger attached, run the code to the point it hangs, interrupt PHP so you return to the debugger, and get a backtrace? Hopefully that will help identify what sort of loop is involved. ------------------------------------------------------------------------ [2020-11-17 19:41:20] mav2287 at aol dot com In case it isn't clear when using the sample script once you execute "$newDate = $date->modify('last day of this month');" PHP will hang. You will never get the chance to go to the next step of the script and do "php > var_dump($newDate);" as the object is never created, ------------------------------------------------------------------------ [2020-11-17 19:38:15] mav2287 at aol dot com Description: ------------ As discovered and documented via the Mac Ports project ( see ticket url below ) php versions 7.3.23 & 7.4.11 and newer seem to create a process with runaway CPU usage when attempting to get the last day of the month. This runaway process seems to continue indefinitely and consumes 100% cpu. Orignal Mac Ports Ticket: https://trac.macports.org/ticket/61351 Test script: --------------- # php -a Interactive shell php > $date = new \DateTime(); php > $newDate = $date->modify('last day of this month'); php > var_dump($newDate); Expected result: ---------------- creation of a DateTime object and a blinking cursor awaiting new command Actual result: -------------- PHP will hang indefinitely and the php process will consume 100% cpu until manually killed ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=80376&edit=1