]> git.ipfire.org Git - thirdparty/postgresql.git/commit
llvmjit: Use explicit LLVMContextRef for inlining
authorDaniel Gustafsson <dgustafsson@postgresql.org>
Fri, 17 Nov 2023 10:47:17 +0000 (11:47 +0100)
committerDaniel Gustafsson <dgustafsson@postgresql.org>
Fri, 17 Nov 2023 10:47:17 +0000 (11:47 +0100)
commit3b991f81c45720515144b928bb8d1f03577628f1
treecd470eb0e19960f2c2f4c0bd72a99efd590f0e95
parentc980eeddccac3f9d7030948569f8d13b6ee1e127
llvmjit: Use explicit LLVMContextRef for inlining

When performing inlining LLVM unfortunately "leaks" types (the
types survive and are usable, but a new round of inlining will
recreate new structurally equivalent types). This accumulation
will over time amount to a memory leak which for some queries
can be large enough to trigger the OOM process killer.

To avoid accumulation of types, all IR related data is stored
in an LLVMContextRef which is dropped and recreated in order
to release all types.  Dropping and recreating incurs overhead,
so it will be done only after 100 queries. This is a heuristic
which might be revisited, but until we can get the size of the
context from LLVM we are flying a bit blind.

This issue has been reported several times, there may be more
references to it in the archives on top of the threads linked
below.

This is a backpatch of 9dce22033d5 to all supported branches.

Reported-By: Justin Pryzby <pryzby@telsasoft.com>
Reported-By: Kurt Roeckx <kurt@roeckx.be>
Reported-By: Jaime Casanova <jcasanov@systemguards.com.ec>
Reported-By: Lauri Laanmets <pcspets@gmail.com>
Author: Andres Freund and Daniel Gustafsson
Discussion: https://postgr.es/m/7acc8678-df5f-4923-9cf6-e843131ae89d@www.fastmail.com
Discussion: https://postgr.es/m/20201218235607.GC30237@telsasoft.com
Discussion: https://postgr.es/m/CAPH-tTxLf44s3CvUUtQpkDr1D8Hxqc2NGDzGXS1ODsfiJ6WSqA@mail.gmail.com
Backpatch-through: v12
src/backend/jit/llvm/llvmjit.c
src/backend/jit/llvm/llvmjit_deform.c
src/backend/jit/llvm/llvmjit_expr.c
src/backend/jit/llvm/llvmjit_inline.cpp
src/include/jit/llvmjit.h
src/include/jit/llvmjit_emit.h