Hello Alexey Serbin, Kudu Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/6874
to look at the new patch set (#9).
Change subject: threadpool: token-based task sequencing
......................................................................
threadpool: token-based task sequencing
This patch adds task sequencing to util/threadpool. Task sequencing allows
M contexts to share a single pool with N threads while also ensuring that
the pool executes tasks belonging to each context in order. Previously this
was only achievable via "one singleton pool per context", which grossly
inflated the total number of threads and overall state.
The new logic is implemented in ThreadPoolToken. Tasks submitted via tokens
are logically grouped together. They may also be sequenced, depending on the
token's execution mode. Tokens expose Wait() variants which will block on
the task group. Tokens may also be shut down before being destroyed, which
has semantics equivalent to shutting down the pool itself (i.e. tasks may no
longer be submitted with these tokens).
Some notes:
- I evaluated two other implementations. In one, tokens had an implicit
lifecycle that was automatically managed by the threadpool. While simpler
for clients, the threadpool was more inefficient with more allocations and
deallocations in each submission. In the other, token submission was built
using regular task submission. This afforded a certain separation between
the "core" of the threadpool and the token logic, but it complicated
locking and tracking of queued tasks.
- I tried to keep submission (whether token-based or tokenless) fast. Just
the change from std::list to std::deque for the main queue ought to
improve performance of tokenless submissions. The next bottleneck is
likely to be lock contention on the global threadpool lock.
Change-Id: If46dc34212027b6ea5dbc2ead7c7af8be57f2c70
---
M src/kudu/util/debug-util.h
M src/kudu/util/threadpool-test.cc
M src/kudu/util/threadpool.cc
M src/kudu/util/threadpool.h
4 files changed, 981 insertions(+), 91 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/74/6874/9
--
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: If46dc34212027b6ea5dbc2ead7c7af8be57f2c70
Gerrit-PatchSet: 9
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Alexey Serbin <aser...@cloudera.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Dan Burkert <danburk...@apache.org>
Gerrit-Reviewer: David Ribeiro Alves <davidral...@gmail.com>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Tidy Bot
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
