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new 7ab9c700a56 [pip][design] PIP-275: Introduce
topicOrderedExecutorThreadNum to deprecate
numWorkerThreadsForNonPersistentTopic in configuration (#20507)
7ab9c700a56 is described below
commit 7ab9c700a5684c489de383b2d370e2ba51a5c5db
Author: houxiaoyu <[email protected]>
AuthorDate: Wed Jun 21 14:05:03 2023 +0800
[pip][design] PIP-275: Introduce topicOrderedExecutorThreadNum to deprecate
numWorkerThreadsForNonPersistentTopic in configuration (#20507)
This is a pip to Introduce `topicOrderedExecutorThreadNum` to deprecate
`numWorkerThreadsForNonPersistentTopic`
---
pip/pip-275.md | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/pip/pip-275.md b/pip/pip-275.md
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+# Background knowledge
+As we can see from the
[doc](https://github.com/apache/pulsar/blob/ac46e2e4fc48dff74233623afa3635ef5285e34d/pulsar-broker-common/src/main/java/org/apache/pulsar/broker/ServiceConfiguration.java#LL1194C16-L1194C72)
that `numWorkerThreadsForNonPersistentTopic` is a configuration to specify the
number of worker threads to serve non-persistent topic.
+Actually, `numWorkerThreadsForNonPersistentTopic` will specify the thread
number of `BrokerService#topicOrderedExecutor`. Initially it was meant only for
non-persistent topics,
+but now it is used for anything that needs to be done under strict order for a
topic, like processing Subscriptions even for a persistent topic:
+* There is only one place invoke `topicOrderedExecutor` for non-persistent
topics.[[1]](https://github.com/apache/pulsar/blob/50b9a93e42e412d9f17b1637287d1a4c7c7ab148/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java#L1706)
+* Other places will invoke `topicOrderedExecutor` for persistent-topic or
persistent-dispatcher.
[[2]](https://github.com/apache/pulsar/blob/50b9a93e42e412d9f17b1637287d1a4c7c7ab148/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentDispatcherMultipleConsumers.java#L141)
[[3]](https://github.com/apache/pulsar/blob/50b9a93e42e412d9f17b1637287d1a4c7c7ab148/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java#L279)
[[4]] [...]
+
+# Motivation
+
+Making this config has a better name and increase the ability of users to
understand what they are configuring.
+
+# High Level Design
+
+Introduce `topicOrderedExecutorThreadNum` to deprecate
`numWorkerThreadsForNonPersistentTopic`.
+
+# Detailed Design
+
+## Design & Implementation Details
+
+### Configuration
+
+* Introduce `topicOrderedExecutorThreadNum` with default value
`Runtime.getRuntime().availableProcessors()`:
+```
+private int topicOrderedExecutorThreadNum =
Runtime.getRuntime().availableProcessors();
+```
+* deprecate `numWorkerThreadsForNonPersistentTopic` and change it's default
value from `Runtime.getRuntime().availableProcessors()` to `-1`:
+```
+private int numWorkerThreadsForNonPersistentTopic = -1;
+```
+* Overwrite method `ServiceConfiguration#getTopicOrderedExecutorThreadNum()`
from lombok.
+```
+public int getTopicOrderedExecutorThreadNum() {
+ return numWorkerThreadsForNonPersistentTopic > 0
+ ? numWorkerThreadsForNonPersistentTopic :
topicOrderedExecutorThreadNum;
+ }
+```
+
+* And all places calling
`ServiceConfiguration#getNumWorkerThreadsForNonPersistentTopic()` will call
`ServiceConfiguration#getTopicOrderedExecutorThreadNum()` instead.
+
+# Backward & Forward Compatibility
+Because we have overwritten method `getTopicOrderedExecutorThreadNum()` from
lombok, so:
+* if user doesn't set the `numWorkerThreadsForNonPersistentTopic`, the value
of worker threads will keep `Runtime.getRuntime().availableProcessors()`
+* If user has set the `numWorkerThreadsForNonPersistentTopic`, the value will
keep what user set before.
+
+
+# Links
+* Mailing List discussion thread:
https://lists.apache.org/thread/hx8v824v5wdoz3kn44s4t9pzgfnqkt1o
+* Mailing List voting thread:
https://lists.apache.org/thread/ywk6z440qt0vs32210799m508gbxfshm
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