#1499: Null pointer dereference in imageio.pmc
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Reporter: arnsholt | Owner: plobsing
Type: bug | Status: new
Priority: normal | Milestone:
Component: none | Version:
Severity: medium | Keywords:
Lang: perl6 | Patch:
Platform: darwin |
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Comment(by plobsing):
Replying to [comment:6 arnsholt]:
> `todo->vtable->whoami` is NULL. I'll add todo->vtable as an attachment,
to keep the comments relatively uncluttered.
Thanks, I've been able to occasionally reproduce the failure using this
configuration. A few observations:
* My todo->vtable has zeroes and 0x80000s in the same places, so this
isn't a totally random piece of memory, just the same piece of memory
taken out of context.
* The intermittent-ness of this bug is what really bothers me. gc_ms is
deterministic, freeze/thaw is deterministic, I certainly hope our math is
deterministic, so where is the randomness coming from?
* This test is *way* too big (from a parrot perspective) for me to get
anything useful done in gdb with watchpoints or breakpoints.
* Boy does rakudo ever copy a lot! And it seems every copy falls back on
default.clone which uses freeze/thaw to copy. Given we now have pluggable
visit system, someone (probably me) can write up a cloning visitor that
won't create an intermediate image, giving you guys faster copies, less
string memory churn, and a probably a nice speedup. Downside: it will
likely hide this bug again.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/1499#comment:8>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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