add Rubocop for style guidelines #3
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clutchski
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Oct 4, 2016
| rake (10.5.0) | ||
| rubocop (0.43.0) |
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these are just dev deps right?
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Yes. Actually the tracer requires third-party libraries only for development: https://github.com/DataDog/dd-trace-rb/pull/3/files#diff-b06e29a984e208fededfd0c6e60ca9ecR35
When the GEM is created, these dependencies are not installed.
p-datadog
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Nov 24, 2024
In the previous PR I mistakenly placed the 'gem' instruction into a spring test. It was intended to be in the cucumber test.
TonyCTHsu
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Nov 24, 2024
In the previous PR I mistakenly placed the 'gem' instruction into a spring test. It was intended to be in the cucumber test.
TonyCTHsu
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Nov 24, 2024
In the previous PR I mistakenly placed the 'gem' instruction into a spring test. It was intended to be in the cucumber test.
ivoanjo
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Dec 2, 2024
**What does this PR do?** This PR raises the minimum Ruby version required for heap profiling from the previous value of >= 2.7 to >= 3.1 due to a new VM bug discovered (see below for details). It's mostly a revert of #3366, where we had first tried to workaround a Ruby 2.7/3.0 bug, but it turns out we missed a spot, and we could trigger VM crashes because of that. **Motivation:** Ruby versions prior to 3.1 had a special optimization called `rb_gc_force_recycle` which would allow objects to directly be garbage collected (e.g. without needing to wait for the GC). It turns out that `rb_gc_force_recycle` did not play well with the changes in Ruby 2.7 to how object ids worked. We uncovered this earlier on during the development of the heap profiler, and put in a workaround for the bug that we thought was enough... Unfortunately, it turns out that the workaround is not enough. The following reproducer, when run on Ruby 2.7 or 3.0 shows how the Ruby VM can segfault inside `id2ref` due to the issue above: ```ruby puts RUBY_DESCRIPTION require "datadog" require "objspace" require "pry" NUM_OBJECTS = 10_000_000 recycled_ids = Array.new(NUM_OBJECTS) { 123 } many_objects = Array.new(NUM_OBJECTS) { Object.new } (0...NUM_OBJECTS).each do |i| recycled_ids[i] = many_objects[i].object_id end puts "Seeded objects!" gets (0...NUM_OBJECTS).each do |i| Datadog::Profiling::StackRecorder::Testing._native_gc_force_recycle(many_objects[i]) many_objects[i] = nil end puts GC.stat puts "Recycled objects!" gets many_objects = nil 10.times { GC.start } Array.new(10_000) { Object.new } 10.times { GC.start } puts GC.stat puts "GC'd objects! (Ruby should have released pages?)" gets recycled_ids.each { |i| begin (nil == ObjectSpace._id2ref(i)) rescue nil end } puts "Done!" ``` Crash details: ``` Program received signal SIGSEGV, Segmentation fault. is_swept_object (ptr=93825033355200, objspace=<optimised out>) at gc.c:3868 3868 return page->flags.before_sweep ? FALSE : TRUE; (gdb) bt #0 is_swept_object (ptr=93825033355200, objspace=<optimised out>) at gc.c:3868 #1 is_garbage_object (objspace=0x55555555d220, objspace=0x55555555d220, ptr=93825033355200) at gc.c:3887 #2 is_live_object (ptr=93825033355200, objspace=0x55555555d220) at gc.c:3909 #3 is_live_object (ptr=93825033355200, objspace=0x55555555d220) at gc.c:3898 #4 id2ref (objid=8264881) at gc.c:3999 #5 os_id2ref (os=<optimised out>, objid=<optimised out>) at gc.c:4019 ``` This crash happens because of two things: 1. Ruby does not clean the object id entry for a recycled object from its internal hash map 2. If the memory page where the object lived is returned back to the OS, trying to `id2ref` on that id will cause Ruby to try to read invalid memory and crash. **Additional Notes:** I've chosen to disable heap profiling on 2.7 and 3.0 because I can't think of a good workaround for the bug above, especially not one that does not increase the overhead of heap profiling. **How to test the change?** This PR updates the test coverage to expect Ruby 3.1+ as the minimum for the feature. You can also quickly validate it doesn't get enabled on the older Rubies using: ``` $ DD_PROFILING_ENABLED=true DD_PROFILING_EXPERIMENTAL_HEAP_ENABLED=true bundle exec ddprofrb exec ruby -e "puts RUBY_DESCRIPTION" W, [2024-12-02T10:42:28.771611 #112585] WARN -- datadog: [datadog] Current Ruby version (3.0.5) cannot support heap profiling due to VM bugs/limitations. Please upgrade to Ruby >= 3.1 in order to use this feature. Heap profiling has been disabled. ```
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What it does
It adds Rubocop as a default tool for style guidelines. Some rules are relaxed because even if they "should" be enforced, at this stage they slow us our review / development cycle. We may enforce other rules later.
Note
chefrepositories to find a kind of "common".rubocop.yml