So, the key here is a compiled method (no longer installed), whose #scaledIdentityHash cannot be used to compute the index in the WeakIdentityKeyDictionary anymore.

The method's hash is 743354880.

The dictionary's internal array's size is 31.

The association of interest is at index 7.

However 743354880 \\ 31 + 1 is not 7 but 22.

There is nothing (i.e. "nil") at index 22.

DebuggerMethodMap class >> #cacheDebugMap:forMethod: cannot work correctly anymore because #keys and #at: are out of sync. :-(

This is scary. Did the object's hash changed without notice? Does it have to do with method compilation and installation?

A manual #rehash solved the issue for now. :-S

VM: 202111302328

VMMaker.oscog-eem.3113

squeak.cog.spur (32-bit)

Best,

Marcel

Am 08.12.2021 15:21:32 schrieb Marcel Taeumel <marcel.taeumel@hpi.de>:
Hi all --

I somehow corrupted my MapCache in DebuggerMethodMap.

This means that I cannot debug anymore:

I know that I can clear that cache. Yet, it is way more fun to understand how that WeakIdentityKeyDictionary behaves that way.

Best,
Marcel