The logs are showing a number of "Scudo OOM" warnings similar to those discussed in #121595. However, none of them have been fatal yet.

In API level 35 the memory allocator no longer prints such an alarming message when this happens. Instead it will just be a one line message like this (llvm/llvm-project#68444):

I/scudo   : Can't populate more pages for size class 8720.

Luckily, in API level 35 they've also added the ability to print the allocator statistics at any time, with code like this (llvm/llvm-project@5759e3c):

import ctypes
ctypes.CDLL(None).mallopt(-205, 0)

Based on those statistics, it doesn't look like Python has a memory leak, as the "inuse" column after the test is roughly the same as it was before. So it's probably just temporary high memory use during the test, causing allocations to be directed to the next highest size class.

On the buildbot about a year ago, these warnings were often associated with crashes. As described in Android/README.md, we worked around this by running the emulator once to create it, then editing its configuration files to increase the emulator RAM from 2 GB to 4 GB. After that, the warnings continued, but the crashes stopped.

But that isn't such a good option on GitHub Actions, because the runner is not persistent, so the extra emulator restart would add about a minute to every CI run. In theory you should be able to avoid this by creating the emulator from a custom hardware profile, but in my experiments, the emulator always ended up with 2 GB of RAM regardless of what it said in the profile.

The tests that trigger this are:

• test.test_ast.test_ast.AST_Tests.test_ast_recursion_limit
• test.test_compile.TestSpecifics.test_compiler_recursion_limit
• test.test_compile.TestSpecifics.test_stack_overflow

These tests all involve parsing an extremely long Python statement. Although they're all skipped on WASM because of limited stack space, reducing the recursion limit does not prevent the warning. What does prevent it is reducing the size of the Python statement, e.g. from 500,000 repetitions to 200,000.

Since I haven't seen these tests crash on GitHub Actions yet, I'm not going to change them just now. If they do start crashing, we can change them to reduce the statement size on Android alone, or even on all platforms if it doesn't significantly reduce the strength of the test.