Disable maximum_function_nesting in Xdebug 3.0+ default settings to be more production-alike
#623
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The `xdebug.max_nesting_level` flag is a problematic flag that, while helping many people avoiding infinite recursion bugs in their code, does not prevent such problems in production environment, and leads to diverging runtime behavior between development and production environments. In practice, many un-experienced users usually install Xdebug, then run some off-the-shelf tool from somewhere, and they experience a crash that requires re-configuring Xdebug to either have a higher `max_nesting_level` or to be `-1` by default. This limit has initially been `100` (before Xdebug 2.3), then raised to `256`, and in general will keep raising as recursive execution usage increases. By disabling this behavior in the **default** configuration of Xdebug (feature still exists, if the end user willingly enables it), we align the behavior of complex recursive execution schemes in production environments to what developers run in their local environment.
Ocramius
changed the title
maximum_function_nesting in Xdebug 3.0+ default settings to make Xdebug more production-alike
Ocramius
changed the title
maximum_function_nesting in Xdebug 3.0+ default settings to make Xdebug more production-alikemaximum_function_nesting in Xdebug 3.0+ default settings to be more production-alike
| @@ -755,7 +758,7 @@ | |||
| ; -> <response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/db ... ></response> | |||
| ; | |||
| ; | |||
| ;xdebug.remote_log = | |||
| ;xdebug.remote_log = | |||
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These were butchered by my editor: is that a problem for this patch?
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The file is auto generated from the docs, as per the first few lines:
; This file is generated by the 'xdebug.org:html/docs/convert.php' robot
; for Xdebug 3.0.0-dev — do not modify by hand
The docs live in the xdebug.org repository, but don't worry about that, I can fix that myself.
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Discussed this with @derickr @ https://chat.stackoverflow.com/transcript/message/50171493#50171493 In practice, Xdebug 3.0 will have multiple "modes", where the default mode has the recursion limit disabled. If that's the case (not sure if tests are needed), then this patch is potentially redundant with the new defaults, which already makes me super-happy 👍 |
| @@ -0,0 +1,17 @@ | |||
| --TEST-- | |||
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Note: this test is still valid, as it demonstrates that a nesting level of 10000 is ignored by the defaults
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I am closing this PR because I don't want to the "maximum function nesting" feature to be an opt-in in "develop" mode. That mode of Xdebug is specifically there to assist in making sure your PHP does not crash — and it has saved my own goat plenty of times. If Xdebug 3's develop mode is not active, the nesting level should not kick in (but it currently does, I think, so I added a ticket). In Xdebug 3 I have also already changed the error message so that it is obvious that it is Xdebug that triggers this. |
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Just a follow-up for reference: run your process with |
The
xdebug.max_nesting_levelsetting is a problematic flag-alike that, whilesometimes helping in avoiding infinite recursion bugs,
does not prevent such problems in production environment, and leads
to diverging runtime behavior between development and production
environments.
In practice, many un-experienced users usually install Xdebug, then run
some off-the-shelf tool from somewhere, and they experience a crash that
requires re-configuring Xdebug to either have a higher
max_nesting_levelor to be
-1by default.This limit has initially been
100(before Xdebug 2.3), then raised to256, and in general will keep raising as recursive execution usage increases.By disabling this behavior in the default configuration of Xdebug (feature
still exists, if the end user willingly enables it), we align the behavior
of complex recursive execution schemes in production environments to what
developers run in their local environment.
Note: users will still run into memory consumption issues due to stack frame
allocation, but at least that's the default behavior of PHP with or without Xdebug
installed.
Related: laminas/laminas-cli#40
/cc @boesing @geerteltink @weierophinney