jaydoane commented on code in PR #5448: URL: https://github.com/apache/couchdb/pull/5448#discussion_r1974002881
########## src/docs/src/whatsnew/3.5.rst: ########## @@ -0,0 +1,172 @@ +.. Licensed under the Apache License, Version 2.0 (the "License"); you may not +.. use this file except in compliance with the License. You may obtain a copy of +.. the License at +.. +.. http://www.apache.org/licenses/LICENSE-2.0 +.. +.. Unless required by applicable law or agreed to in writing, software +.. distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +.. WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +.. License for the specific language governing permissions and limitations under +.. the License. + +.. _release/3.5.x: + +============ +3.5.x Branch +============ + +.. contents:: + :depth: 1 + :local: + +.. _release/3.5.0: + +Version 3.5.0 +============= + +Highlights +---------- + +* :ghissue:`5399`, :ghissue:`5441`, :ghissue:`5443`: Implement parallel + ``pread`` calls: lets clients issue concurrent ``pread`` calls without blocking + each other or having to wait for all writes and ``fsync`` calls. This is + enabled by default and can be disabled with ``[couchdb] use_cfile = false`` in + the configuration. + + CouchDB already employs a multiple-parallel-read and concurrent serial-write + design at the database engine layer, but below that in the storage engine, + each file representing a database shard is required to route all read / write + / sync requests through a single Erlang process that owns the file descriptor + (fd). + + An Erlang process can at most execute at the speed of a single CPU core. Two + scenarios can lead to a starvation of the fd-owning Erlang process message + inbox: + + - 1000s concurrent read requests with a constant stream of writes per shard, Review Comment: ```suggestion - 1000s of concurrent read requests with a constant stream of writes per shard, ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
