multi threading GxB_WILL_WAIT and GrB_Matrix_wait

[AviAvni]

I think I found a concurrency issue
if calling GrB_Matrix_wait
and in another thread run GrB_Matrix_get_INT32 with GxB_WILL_WAIT on the same matrix it returns GrB_INVALID_OBJECT

[DrTimothyAldenDavis]

That’s not a bug but a feature per the GraphBLAS spec. A matrix can be accessed by multiple threads only after a single thread has done a wait on the matrix. Any concurrent access to a matrix before the wait is undefined. That holds even if the matrix is an input to any GrB method. So if the matrix has not had a last call of GrB_Matrix_wait only the owning thread can call GrB get to ask the WILL_WAIT state. Sent from Gmail Mobile

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On Fri, May 15, 2026 at 2:52 AM Avi Avni ***@***.***> wrote: *AviAvni* created an issue (DrTimothyAldenDavis/GraphBLAS#446) <#446> I think I found a concurrency issue if callingGrB_Matrix_wait and in another thread run GrB_Matrix_get_INT32 with GxB_WILL_WAIT on the same matrix it returns GrB_INVALID_OBJECT — Reply to this email directly, view it on GitHub <#446>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEYIIOIGTK3UYDI3RH53SV3423EFLAVCNFSM6AAAAACY7CU74CVHI2DSMVQWIX3LMV43ASLTON2WKOZUGQ2TEMRWHEZDGMQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[DrTimothyAldenDavis]

We can talk about it sometime to see what can be done to use WILL_WAIT appropriately.