Known flaky tests patterns. These patterns are derived from fbcode real tests, ideally the size of the folder should grow, while the flaky tests in fbcode should shrink.

The bind(2) syscall allow specify a port number, however, using arbitrary or random number could cause bind fail with -EADDRINUSE, or flakiness for tests, because it may not always fail.

One mitigation is use Linux network namespace, and mount a private network so that the test with sockets could still work unless it uses external network.

However, the test should not rely on network namespace, instead of binding an arbitrary port, the test could also bind with zero, which kernel will assign next available port hence it would always success. The port number can be retrieved by calling getsockname(2).

Same tests use a for loop for bind: always retry with next port when bind returns -EADDRINUSE, this is less ideal, not only it is brute force, but also it may cause TOCTOU issue.