---
title: Troubleshooting the Ruby Profiler
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Continuous Profiler > Profiler Troubleshooting > Troubleshooting the
  Ruby Profiler
---

# Troubleshooting the Ruby Profiler

## Missing profiles in the profile search page{% #missing-profiles-in-the-profile-search-page %}

If you've configured the profiler and don't see profiles in the profile search page, turn on [debug mode](https://docs.datadoghq.com/tracing/troubleshooting/#debugging-and-logging) and [open a support ticket](https://docs.datadoghq.com/help/) with debug files and the following information:

- Operating system type and version (for example, Ubuntu Linux 24.04)
- Runtime type, version, and vendor (for example, Ruby 3.3.1)

## Missing profiles for Resque jobs{% #missing-profiles-for-resque-jobs %}

When profiling [Resque](https://github.com/resque/resque) jobs, you should set the `RUN_AT_EXIT_HOOKS` environment variable to `1`, as described in the [Resque documentation](https://github.com/resque/resque/blob/v2.0.0/docs/HOOKS.md#worker-hooks).

Without this flag, profiles for short-lived Resque jobs will be unavailable.

## Profiling does not turn on because compilation of the Ruby VM just-in-time header failed{% #profiling-does-not-turn-on-because-compilation-of-the-ruby-vm-just-in-time-header-failed %}

There is a known incompatibility between Ruby 2.7 and older GCC versions (4.8 and below) that impacts the profiler ([upstream Ruby report](https://bugs.ruby-lang.org/issues/18073), [`dd-trace-rb` bug report](https://github.com/DataDog/dd-trace-rb/issues/1799)). This can result in the following error message: "Your ddtrace installation is missing support for the Continuous Profiler because compilation of the Ruby VM just-in-time header failed. Your C compiler or Ruby VM just-in-time compiler seem to be broken."

To fix this, update your operating system or Docker image so that the GCC version is something more recent than v4.8.

For further help with this issue, [contact support](https://docs.datadoghq.com/help/) and include the output of running `DD_PROFILING_FAIL_INSTALL_IF_MISSING_EXTENSION=true gem install datadog` and the resulting `mkmf.log` file.

## Frames omitted when backtraces are very deep{% #frames-omitted-when-backtraces-are-very-deep %}

The Ruby profiler truncates deep backtraces when collecting profiling data. Truncated backtraces are missing some of their caller functions, making it impossible to link them to the root call frame. As a result, truncated backtraces are grouped together under a `Truncated Frames` (or `N frames omitted` in older versions) frame.

You can increase the maximum backtrace (stack) depth with the `DD_PROFILING_MAX_FRAMES` environment variable, or in code:

```ruby
Datadog.configure do |c|
  c.profiling.advanced.max_frames = 600
end
```

## Unexpected failures or errors from Ruby gems that use native extensions{% #unexpected-failures-or-errors-from-ruby-gems-that-use-native-extensions %}

The Ruby profiler gathers data by sending `SIGPROF` UNIX signals to Ruby applications, enabling finer-grained data gathering.

Sending `SIGPROF` is a common profiling approach, and may cause system calls from native extensions/libraries to be interrupted with a system [`EINTR` error code](https://man7.org/linux/man-pages/man7/signal.7.html#:~:text=Interruption%20of%20system%20calls%20and%20library%20functions%20by%20signal%20handlers). Rarely, native extensions or libraries called by them may have missing or incorrect error handling for the `EINTR` error code.

The following incompatibilities are known:

- Using the `mysql2` gem together with versions of `libmysqlclient` [older than 8.0.0](https://bugs.mysql.com/bug.php?id=83109). The affected `libmysqlclient` version is known to be present on Ubuntu 18.04, but not 20.04 or later releases.
- [Using the `rugged` gem.](https://github.com/DataDog/dd-trace-rb/issues/2721)
- Using the `passenger` gem/Phusion Passenger web server [older than 6.0.19](https://github.com/DataDog/dd-trace-rb/issues/2976)
- [Some APIs in the `Dir` class](https://github.com/DataDog/dd-trace-rb/issues/3450)

In these cases, the latest version of the profiler automatically detects the incompatibility and applies a workaround.

If you encounter failures or errors from Ruby gems that use native extensions other than those listed above, you can manually enable the "no signals" workaround, which avoids the use of `SIGPROF` signals. To enable this workaround, set the `DD_PROFILING_NO_SIGNALS_WORKAROUND_ENABLED` environment variable to `true`, or in code:

```ruby
Datadog.configure do |c|
  c.profiling.advanced.no_signals_workaround_enabled = true
end
```

Let our team know if you find or suspect any incompatibilities [by opening a support ticket](https://docs.datadoghq.com/help/). Doing this enables Datadog to add them to the auto-detection list, and to work with the gem/library authors to fix the issue.

## Segmentation faults in `gc_finalize_deferred` in Ruby versions 2.6 to 3.2{% #segmentation-faults-in-gc_finalize_deferred-in-ruby-versions-26-to-32 %}

A workaround for this issue is automatically applied since [`dd-trace-rb` version 1.21.0](https://github.com/datadog/dd-trace-rb/releases/tag/v1.21.0). Datadog recommends upgrading to this version or later to fix this issue.

Prior to version 1.21.0, in rare situations the profiler could trigger [Ruby VM Bug #19991](https://bugs.ruby-lang.org/issues/19991) that manifests itself as a "Segmentation fault" with a crash stack trace including the `gc_finalize_deferred` function.

This bug has been fixed for Ruby 3.3 and above. For older Ruby versions (and prior to dd-trace-rb 1.21.0), you can use the "no signals" workaround to resolve this issue.

To enable this workaround, set the `DD_PROFILING_NO_SIGNALS_WORKAROUND_ENABLED` environment variable to `true`, or in code:

```ruby
Datadog.configure do |c|
  c.profiling.advanced.no_signals_workaround_enabled = true
end
```

## Further Reading{% #further-reading %}

- [APM Troubleshooting](https://docs.datadoghq.com/tracing/troubleshooting)