From: "ivoanjo (Ivo Anjo)" <noreply@...>
Date: 2022-11-09T11:19:00+00:00
Subject: [ruby-core:110669] [Ruby master Bug#19114] Calling TracePoint#enable multiple times causes TracePoint to be activated multiple times

Issue #19114 has been reported by ivoanjo (Ivo Anjo).

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Bug #19114: Calling TracePoint#enable multiple times causes TracePoint to be activated multiple times
https://bugs.ruby-lang.org/issues/19114

* Author: ivoanjo (Ivo Anjo)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.0preview2 (2022-09-09 master 35cfc9a3bb) [x86_64-darwin20]
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
Howdy ����! I work for Datadog [on the `ddtrace` gem](https://github.com/DataDog/dd-trace-rb) and I found an issue with TracePoint.

### Background

For tracking time spent in Garbage Collection on our Ruby profiler, we use a tracepoint. While doing some experiments around our code, I realized that enabling the same `TracePoint` more than once made it trigger multiple times.

### How to reproduce (Ruby version & script)

This can be reproduced with any tracepoint:

```ruby
puts RUBY_DESCRIPTION
puts "Enabling tracepoint"
tracepoint = TracePoint.new(:line) { |tp| p [tp.path, tp.lineno, tp.event] }.tap(&:enable)
5.times { tracepoint.enable }
puts "Finished!"
```

### Expectation and result

This is the output of the above script:

```
ruby 3.2.0preview2 (2022-09-09 master 35cfc9a3bb) [x86_64-darwin20]
Enabling tracepoint
["<internal:kernel>", 91, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["<internal:trace_point>", 213, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["triggertracepoint.rb", 4, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["<internal:trace_point>", 213, :line]
["triggertracepoint.rb", 5, :line]
["triggertracepoint.rb", 5, :line]
["triggertracepoint.rb", 5, :line]
["triggertracepoint.rb", 5, :line]
["triggertracepoint.rb", 5, :line]
["triggertracepoint.rb", 5, :line]
Finished!
```

My expectation is that once enabled, a `TracePoint` fires only once for each event, regardless of how many times `TracePoint#enable` was called. Instead, I see it being called as many times as `#enable` was called.




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