Frequent segfaults in CI / Ubuntu

[tinchodias]

Since last week. Always in SDL_Surface>pixels sent from SDL2 host loop:

Example:

       0x300017af0 M ExternalAddress>pointerAt: 0x3610d8bf0: a(n) ExternalAddress
       0x300017b30 M SDL_Surface>pixels 0x3610d8c00: a(n) SDL_Surface
       0x300017b80 M BlOSWindowSDL2BufferSurfaceRenderer>initializeForSurface: 0x3610d8b70: a(n) BlOSWindowSDL2BufferSurfaceRenderer
       0x300017bc0 M BlHostRendererBufferSurface(BlHostRendererSurface)>newSurfaceRendererOn: 0x3610d7ee0: a(n) BlHostRendererBufferSurface
       0x300017bf8 M BARenderer>initializeForHostSpace: 0x3610c3830: a(n) BARenderer
       0x300017c30 M BlOSWindowSDL2HostSpace(BlOSWindowHostSpace)>initializeRenderer 0x3610c1098: a(n) BlOSWindowSDL2HostSpace
       0x300017c60 M BlSpaceFrameDrawingValidationPhase>runOn: 0x3610ae998: a(n) BlSpaceFrameDrawingValidationPhase
       0x300017c98 M BlSpaceFrame>runCurrentPhaseOn: 0x3610ae920: a(n) BlSpaceFrame
       0x300017cd0 M BlSpaceFrame>runOn: 0x3610ae920: a(n) BlSpaceFrame
       0x300017d08 M BlSpace>processPulse 0x3610ae6d0: a(n) BlSpace
       0x300017d38 M BlSpace>pulse 0x3610ae6d0: a(n) BlSpace
       0x300017d68 M [] in BlParallelUniverse>pulseSynchronously 0x3600aada0: a(n) BlParallelUniverse
       0x300017db8 M OrderedCollection>do: 0x3600e28c8: a(n) OrderedCollection
       0x300017df0 M [] in BlParallelUniverse>pulseSynchronously 0x3600aada0: a(n) BlParallelUniverse
       0x300017e20 M FullBlockClosure(BlockClosure)>on:do: 0x3610d7a28: a(n) FullBlockClosure
       0x300017e60 M BlParallelUniverse>pulseSynchronously 0x3600aada0: a(n) BlParallelUniverse
       0x300017e90 M BlParallelUniverse>pulse 0x3600aada0: a(n) BlParallelUniverse

(https://github.com/pharo-graphics/Bloc/actions/runs/13151812937/job/36700465026)

[tinchodias]

In Windows, what we see often is a random:

BATextMeasurerTest
 ✗ #testIndexAtBetweenAllCharactersInRealPointWithDot (0ms)
TestFailure: Got #(0 1 2 3 4 5 6 7 7) instead of #(0 1 2 3 4 5 6 7 8).
BATextMeasurerTest(TestAsserter)>>assert:description:resumable:
BATextMeasurerTest(TestAsserter)>>assert:description:
BATextMeasurerTest(TestAsserter)>>assert:equals:
BATextMeasurerTest>>testIndexAtBetweenAllCharactersInRealPointWithDot ...assert: theIndices equals: (0 to: aParagraph text size) asArray
BATextMeasurerTest(TestCase)>>performTest

(https://github.com/pharo-graphics/Bloc/actions/runs/13150839451/job/36697880901?pr=682)

[tinchodias]

I tried to reproduce the crash on Debian and I couldn't.
First I did it in the UI, running all tests. Later, I read more carefully a log and the crash seemed to occur in a test in BlSpaceSmokeTest. I tried it on the command-line but never got segfault:

./pharo Pharo.image eval "BlSpaceSmokeTest suite run"

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EDIT: this is a Debian GNU/Linux 12 (bookworm)