add additional location tracking to Arc, alloc, and mpsc
#265
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Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
This allows it to be distinguished from other arcs from the same location. Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
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carllerche
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May 9, 2022
hawkw
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May 10, 2022
# 0.5.5 (May 10, 2022) ### Added - sync: Add `Arc::from_std` without `T: Sized` bound (#226) - sync: Implement `Debug` for `AtomicPtr` for all `T` (#255) - logs: Add location tracking for threads and atomic operations (#258) - logs: Add additional location tracking to `Arc`, `alloc`, and `mpsc` (#265) - logs: Improve `tracing` configuration for `LOOM_LOG` (#266) - logs: Add a span for the current model's iteration (#267) ### Documented - Add note about in-memory representation of atomic types (#253) - Document `LOOM_LOG` syntax (#257) ### Fixed - Fix double panic when exceeding the branch limit in `Drop` (#245) - cell: Allow using `{Mut,Const}Ptr::{deref,with}` when the pointee is `!Sized` (#247) - thread: Fix semantics of `thread::park` after `Thread::unpark` (#250)
hawkw
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May 13, 2022
# 0.5.5 (May 10, 2022) ### Added - sync: Add `Arc::from_std` without `T: Sized` bound (#226) - sync: Implement `Debug` for `AtomicPtr` for all `T` (#255) - logs: Add location tracking for threads and atomic operations (#258) - logs: Add additional location tracking to `Arc`, `alloc`, and `mpsc` (#265) - logs: Improve `tracing` configuration for `LOOM_LOG` (#266) - logs: Add a span for the current model's iteration (#267) ### Documented - Add note about in-memory representation of atomic types (#253) - Document `LOOM_LOG` syntax (#257) ### Fixed - Fix double panic when exceeding the branch limit in `Drop` (#245) - cell: Allow using `{Mut,Const}Ptr::{deref,with}` when the pointee is `!Sized` (#247) - thread: Fix semantics of `thread::park` after `Thread::unpark` (#250)
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Motivation
Currently, loom's mock
Arcwill track the source code location wherethe
Arcwas created. This is useful for diagnosing problems, but itisn't always enough to make the output easy to understand.
In particular,
LOOM_LOG=tracewill indicate where theArcwascreated, and will log ref count operations on that
Arc. The creationlocation is useful , but ref count operations aren't associated with a
location --- so a user reading the log cannot determine where the
Arc's reference count was incremented or decremented from. This makestracking leaks difficult.
Additionally, in the
LOOM_LOGoutput, eachArcinstance isidentified by its
Ref(an index in the store of loom object states).This permits tracking an individual
Arc's refcount lifecycle in thelogs. However, when a leak is detected, the panic message does not
include this index, so it's not possible to determine which particular
Arcwas leaked. The location where theArcwas created is included,but multiple
Arcs may have originated from the same location.Solution
This branch improves
Arcdebuggability by adding location tracking tooperations that increment and decrement the
Arc's reference count. Italso adds the index in the object store to the panic message when a leak
is detected, so the user can now go back and look for all the events for
the
Arcinstance with that ID. This should make debuggingArcleaksmuch easier.
Similarly, I've also added location tracking to Loom's
allocandmpscmocks, and modified their panic messages to print the store indexas well.