## A Multithreaded, Transaction-Based Locking Strategy for Containers Bob Steagall CppCon 2020 KEWB COMPUTING ## Overview • Sharing a container among multiple threads • A motivating problem • Some than ever ## Sharing a Container – Avoiding Race Conditions • If all threads are readers... • No locking is required • If the number of reads is much larger than the number of writes... • We might be writes? • A per-element mutex strategy might work... • ... if a given write operation requires locking exactly one element ## Sharing a Container – Avoiding Race Conditions • What about the case where

from repodata.jlap; implies 'lock'. lock: use locking when reading, updating index (repodata.json) cache. Now enabled. --no-lock Disable locking when reading, updating index (repodata.json) cache from repodata.jlap; implies 'lock'. lock: use locking when reading, updating index (repodata.json) cache. Now enabled. --no-lock Disable locking when reading, updating index (repodata.json) cache from repodata.jlap; implies 'lock'. lock: use locking when reading, updating index (repodata.json) cache. Now enabled. --no-lock Disable locking when reading, updating index (repodata.json) cache

Copied Value ■ Thread-Specific Storage ■ Future ## Dealing with Mutation ■ Scoped Locking ■ Strategized Locking ■ Thread-Safe Interface ■ Guarded Suspension Active Object Monitor Object Reactor Thread-Specific Storage ■ Future Active Object ## Dealing with Mutation ■ Scoped Locking ■ Strategized Locking ■ Thread-Safe Interface Monitor Object ■ Guarded Suspension Reactor ## Copied Value Mutation ■ Scoped Locking ■ Strategized Locking Monitor Object ■ Thread-Safe Interface ■ Guarded Suspension Reactor ## Scoped Locking ## Scoped Locking is RAI applied to locking ## I dea: - Bind

of the pessimistic transaction model is that for scenarios with high conflict rates, the cost of locking ahead is less than the cost of rollback afterwards. Moreover, it can solve the problem that multiple Continuous Replication from Databases that Use gh-ost or pt-osc In production scenarios, table locking during DDL execution can block the reads from or writes to the database to a certain extent. Therefore item|Description| |---|---| |pessimistic|Determines whether to enable the pipelined pessimistic locking process| |pessimistic|Determines whether to enable the in memory pessimistic lock| |pessimistic|Controls

generating mo files in repository. • Translation process • Suggestion voting • Translation locking • Checks and fixups • Custom automatic fixups • Customizing checks • Fine contain example.com as domain? ## Enable indexing offloading Enable OFFLOAD INDEXING to prevent locking issues and improve performance. Don’t forget to schedule indexing in background job to keep the index translation for translating [Users, Managers] Can lock translation while translating (see Translation locking). Can add suggestion [Users, Managers, Guests] Can add new suggestions. Can use machine translation

contain example.com as domain? ## Enable indexing offloading Enable OFFLOAD_INDEXING to prevent locking issues and improve performance. Don’t forget to schedule indexing in background job to keep the index for translating [Users, Managers, Owners] Can lock translation while translating (see Translation locking). Can add suggestion [Users, Managers, Owners, Guests] Can add new suggestions. Can use machine OFFLOAD INDEXING. The first approach (immediate updates) allows more up to date index, but suffers locking issues in some setup (e.g., Apache's mod_wski) and produces more fragmented index. Offloaded

already translated strings or not. |Recent changes|Search|Files|Automatic translation|Git maintenance|Locking|Share|Activity| |---|---|---|---|---|---|---|---| ## Download You can download file for offline contain example.com as domain? ## Enable indexing offloading Enable OFFLOAD_INDEXING to prevent locking issues and improve performance. Don’t forget to schedule indexing in background job to keep the index translation for translating [Users, Managers] Can lock translation while translating (see Translation locking). Can add suggestion [Users, Managers, Guests] Can add new suggestions. Can use machine translation

use PostgreSQL - MySQL or MariaDB - Unicode issues in MySQL - Transaction locking - Creating database in MySQL - Configuring Weblate to use MySQL - Other configurations generating mo files in repository • Translation process • Suggestion voting • Translation locking • Additional information on source strings • Strings_prioritization • Quality_check utf8mb4 by: ALTER DATABASE weblate CHARACTER SET utf8mb4; ## Transaction locking MySQL by default uses has different transaction locking scheme than other databases and in case you see errors like Deadlock

use PostgreSQL - MySQL or MariaDB - Unicode issues in MySQL - Transaction locking - Creating database in MySQL - Configuring Weblate to use MySQL - Other configurations generating mo files in repository • Translation process • Suggestion voting • Translation locking • Additional information on source strings • Strings_prioritization • Quality utf8mb4 by: ALTER DATABASE weblate CHARACTER SET utf8mb4; ## Transaction locking MySQL by default uses has different transaction locking scheme than other databases and in case you see errors like Deadlock

use PostgreSQL - MySQL or MariaDB - Unicode issues in MySQL - Transaction locking - Creating database in MySQL - Configuring Weblate to use MySQL - Other configurations generating mo files in repository • Translation process • Suggestion voting • Translation locking • Additional information on source strings • Strings prioritization • Quality utf8mb4 by: ALTER DATABASE weblate CHARACTER SET utf8mb4; ## Transaction locking MySQL by default uses has different transaction locking scheme than other databases and in case you see errors like Deadlock