From f34a17fb355d7eb570f298fd073ddb089552b608 Mon Sep 17 00:00:00 2001 From: Tor Egge Date: Thu, 24 Mar 2022 13:15:18 +0100 Subject: Add comment to tsan-suppressions.txt describing why we suppress deadlock warning related to attribute context lock and enumerated attribute enum lock. --- tsan-suppressions.txt | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/tsan-suppressions.txt b/tsan-suppressions.txt index 23b63b8945c..7ea210ced93 100644 --- a/tsan-suppressions.txt +++ b/tsan-suppressions.txt @@ -5,6 +5,24 @@ deadlock:storage::MergeThrottler::onFlush +# We hold the attribute context lock when getting a shared lock on +# enumerated attributes to prevent references to enumerated values +# from being changed due to compaction while performing grouping on +# the attribute. Thus we have an apparent lock order cycle between the +# attribute context lock and the shared lock on each attribute. +# +# We use an interlock to ensure that only one thread at a time tries +# to get an exclusive lock on an enumerated attribute (before +# compacting the enum store). Without that interlock, we could get a +# deadlock with +# +# Thread A having shared lock on attribute E and trying to get a shared lock +# on attribute F, blocked by thread D. +# Thread B having shared lock on attribute F and trying to get a shared lock +# on attribute E, blocked by thread C. +# Thread C trying to get exclusive lock on attribute E, blocked by thread A +# Thread D trying to get exclusive lock on attribute F, blocked by thread B + deadlock:search::AttributeContext::getAttribute deadlock:search::AttributeContext::getAttributeStableEnum deadlock:proton::ImportedAttributesContext::getAttribute -- cgit v1.2.3