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Date: Tue, 24 Mar 2020 14:20:08 +0100
From: Julio Guerra <>
Subject: Re: [Bug] Do not ignore membarrier return code

Hello Rich,

Here are more details on what we did to reproduce the issue.
You can clone this gist
and have a look at the file example in order to get started
with it. The test.js file does a require of the js bindings of grpc,
which involves the dlopen.

What we observed yesterday with this example was:
- It crashed approximately 9 times out of 10 on aws codebuild with the
machine BUILD_GENERAL1_SMALL (3 GB memory, 2 vCPUs).
- It worked all the time by only adding membarrier to the seccomp
profile of the docker run.

But I wanted to give you more details with stack traces of the
segfault by retrying today with gdb but I cannot reproduce it
I'll retry later to see if I see the error again...

If what you say about membarrier is true, I think there may be some
synchronization side-effect of the syscall since, afaik, node uses
threads in order to load the shared libraries in the libuv.


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