Our test framework, like most such frameworks, forks a child process for each test run. This helps avoid cross contamination between failing tests. However, when we time out a test and collect cores, we only core the parent process, which is usually in a boring "I started the child and am waiting for it to finish". state. All the interesting information about a hung test is in the child process, for which we don't get a core. See BF-41413 for an example.