Make sense to me Enrico
Il giorno gio 26 mag 2022 alle ore 08:31 Yubiao Feng <yubiao.f...@streamnative.io.invalid> ha scritto: > > I open a pip to discuss Auto release client useless connections, could you > help me review > > > ## Motivation > Currently, the Pulsar client keeps the connection even if no producers or > consumers use this connection. > If a client produces messages to topic A and we have 3 brokers 1, 2, 3. Due > to the bundle unloading(load manager) > topic ownership will change from A to B and finally to C. For now, the > client-side will keep 3 connections to all 3 brokers. > We can optimize this part to reduce the broker side connections, the client > should close the unused connections. > > So a mechanism needs to be added to release unwanted connections. > > ### Why are there idle connections? > > 1.When configuration `maxConnectionsPerHosts ` is not set to 0, the > connection is not closed at all. > The design is to hold a fixed number of connections per Host, avoiding > frequent closing and creation. > > https://github.com/apache/pulsar/blob/72349117c4fd9825adaaf16d3588a695e8a9dd27/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConnectionPool.java#L325-L335 > > 2-1. When clients receive `command-close`, will reconnect immediately. > It's designed to make it possible to reconnect, rebalance, and unload. > > https://github.com/apache/pulsar/blob/72349117c4fd9825adaaf16d3588a695e8a9dd27/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConnectionHandler.java#L122-L141 > > 2-2. The broker will close client connections before writing ownership info > to the ZK. Then clients will get deprecated broker address when it tries > lookup. > > https://github.com/apache/pulsar/blob/72349117c4fd9825adaaf16d3588a695e8a9dd27/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java#L1282-L1293 > > ## Goal > Automatically release connections that are no longer used. > > - Scope > - **Pulsar client** > Contains connections used by consumers, Producers, and Transactions. > > - **Pulsar proxy** > Contains only the connection between Proxy and broker > > ## Approach > Periodically check for idle connections and close them. > > ## Changes > > ### API changes > **ClientCnx** added an idle check method to mark idle time. > > ```java > /** Create time. **/ > private final long createTime; > /** The time when marks the connection is idle. **/ > private long IdleMarkTime; > /** The time when the last valid data was transmitted. **/ > private long lastWorkTime; > /** Stat. enumerated values: using, idle_marked, before_release, released**/ > private int stat; > /** > * Check client connection is now free. This method may change the state > to idle. > * This method will not change the state to idle. > */ > public boolen doIdleCheck(); > /** Get stat **/ > public int getStat(); > /** Change stat **/ > public int setStat(int originalStat, int newStat); > ``` > > ### Configuration changes > We can set the check frequency and release rule for idle connections at > `ClientConfigurationData`. > > ```java > @ApiModelProperty( > name = "autoReleaseIdleConnectionsEnabled", > value = "Do you want to automatically clean up unused connections" > ) > private boolean autoReleaseIdleConnectionsEnabled = true; > > @ApiModelProperty( > name = "connectionMaxIdleSeconds", > value = "Release the connection if it is not used for more than > [connectionMaxIdleSeconds] seconds" > ) > private int connectionMaxIdleSeconds = 180; > > @ApiModelProperty( > name = "connectionIdleDetectionIntervalSeconds", > value = "How often check idle connections" > ) > private int connectionIdleDetectionIntervalSeconds = 60; > ``` > > ## Implementation > > - **Pulsar client** > If no consumer, producer, or transaction uses the current connection, > release it. > > - **Pulsar proxy** > If the connection has not transmitted valid data for a long time, release > it. > > > Yubiao Feng > Thanks
