[NO-TICKET] Upgrade to libdatadog 14.0 #4065
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**What does this PR do?** This PR upgrades the libdatadog dependency to the latest 14.0 release. It also updates our API usage to match some 13.1 -> 14.0 changes. **Motivation:** The libdatadog 14.0 release includes a number of improvements to the crashtracking implementation, and we want to pick them up. **Additional Notes:** As a first pass, I've disabled the creation and use of the alt stack, to match our existing setup. I did not yet experiment with `use_alt_stack = true`. **How to test the change?** Existing test coverage should be enough to cover our libdatadog API usage.
ivoanjo
added
core
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #4065 +/- ##
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Coverage 97.72% 97.73%
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Files 1338 1338
Lines 80248 80248
Branches 4016 4016
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+ Hits 78426 78432 +6
+ Misses 1822 1816 -6 ☔ View full report in Codecov by Sentry. |
BenchmarksBenchmark execution time: 2024-11-06 09:48:19 Comparing candidate commit ddbbbcb in PR branch Found 0 performance improvements and 1 performance regressions! Performance is the same for 28 metrics, 2 unstable metrics. scenario:tracing - 100 span trace - no writer
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Strech
approved these changes
Nov 5, 2024
I've dropped a note to @sanchda which has been doing a lot of working on libdatadog crashtracking so he can do a quick pass on that part as well :) |
p-datadog
approved these changes
Nov 5, 2024
p-datadog
approved these changes
Nov 5, 2024
|
I spent some time looking into Since the Ruby VM itself sets an altstack, this leaves us:
Since the crashtracker is currently off by default, I don't think this should be a blocker for upgrading to libdatadog 14. In preparation for |
I spent some time looking into `use_alt_stack` setting and I think there's a bug in libdatadog and that setting doesn't seem to be doing anything at this point. Since the Ruby VM itself sets an altstack, this leaves us: * In libdatadog 13.1, the crashtracker code always used the altstack (e.g. equivalent of `use_alt_stack` was hardcoded to `true`) => in libdatadog 13.1 we used the Ruby altstack * In libdatadog 14.0, the crashtracker code chooses to use the altstack based on the value of `create_alt_stack` => libdatadog 14.0 we can't use the Ruby altstack In preparation for `use_alt_stack` to get fixed in a future libdatadog release, I'm changing it to true although, right now it's a no-op. This means that in a future libdatadog release, we'll be back to where we were in libdatadog 13.1: the crashtracker DOES NOT create its own altstack, BUT WILL USE the existing Ruby altstack.
AlexJF
approved these changes
Nov 6, 2024
Merged
ivoanjo
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Nov 7, 2024
**What does this PR do?** This PR upgrades the libdatadog dependency to the latest 14.1 release. **Motivation:** This PR fixes the issues we uncovered during testing of 14.0 in #4065: specifically, that triggering a stack overflow with native code would result in incorrect behavior (a segfault, not a stack overflow exception) when crashtracking was enabled. **Additional Notes:** N/A **How to test the change?** Our existing test coverage includes libdatadog testing. The native code stack overflow is a bit of a pain to trigger because GCC seems to like optimizing away such things. What I did was compile the profiler native extension with `export DDTRACE_DEBUG=true` (remember to run clean first!), and then adding the following trivial stack overflow: ```diff diff --git a/ext/datadog_profiling_native_extension/profiling.c b/ext/datadog_profiling_native_extension/profiling.c index 96637cd110..4ec5505147 100644 --- a/ext/datadog_profiling_native_extension/profiling.c +++ b/ext/datadog_profiling_native_extension/profiling.c @@ -38,6 +38,12 @@ static VALUE _native_enforce_success(DDTRACE_UNUSED VALUE _self, VALUE syserr_er static void *trigger_enforce_success(void *trigger_args); static VALUE _native_malloc_stats(DDTRACE_UNUSED VALUE _self); +static VALUE blow_stack(DDTRACE_UNUSED VALUE _self) { + fprintf(stderr, "."); + blow_stack(Qnil); + return Qnil; +} + void DDTRACE_EXPORT Init_datadog_profiling_native_extension(void) { VALUE datadog_module = rb_define_module("Datadog"); VALUE profiling_module = rb_define_module_under(datadog_module, "Profiling"); @@ -72,6 +78,8 @@ void DDTRACE_EXPORT Init_datadog_profiling_native_extension(void) { rb_define_singleton_method(testing_module, "_native_trigger_holding_the_gvl_signal_handler_on", _native_trigger_holding_the_gvl_signal_handler_on, 1); rb_define_singleton_method(testing_module, "_native_enforce_success", _native_enforce_success, 2); rb_define_singleton_method(testing_module, "_native_malloc_stats", _native_malloc_stats, 0); + + rb_define_singleton_method(testing_module, "blow_stack", blow_stack, 0); } ```
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What does this PR do?
This PR upgrades the libdatadog dependency to the latest 14.0 release.
It also updates our API usage to match some 13.1 -> 14.0 changes.
Motivation:
The libdatadog 14.0 release includes a number of improvements to the crashtracking implementation, and we want to pick them up.
Change log entry
Upgraded libdatadog dependency to version 14.0
Additional Notes:
As a first pass, I've disabled the creation and use of the alt stack, to match our existing setup.
I did not yet experiment with
use_alt_stack = true.How to test the change?
Existing test coverage should be enough to cover our libdatadog API usage.