zawodskoj opened a new issue, #1342: URL: https://github.com/apache/plc4x/issues/1342
### What happened? For some reason, if `Bootstrap.connect(...)` had failed for any reason, EventLoopGroup.shutdownGracefullly does not close channel and keeps `select`-ing it indefinitely, causing a lot of logs to appear ``` NioEventLoop -- Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@5bb67f2. NioEventLoop -- Migrated 1 channel(s) to the new Selector. NioEventLoop -- Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@4a67eb86. NioEventLoop -- Migrated 1 channel(s) to the new Selector. NioEventLoop -- Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@748a37b5. NioEventLoop -- Migrated 1 channel(s) to the new Selector. ``` There is a basic repro - it purposely tries to open non-existent serial port and fails: https://gist.github.com/zawodskoj/68987f535bbfe199eeee9be43cf4bf13 There is also a dirty workaround - it is possible to obtain SerialPollingSelector through reflection and invoke `close()` on them, catching meaningless NotImplementedException ```kotlin val getJCh = AbstractNioChannel::class.java.getDeclaredMethod("javaChannel") getJCh.isAccessible = true val javach = getJCh.invoke(cch) as AbstractInterruptibleChannel try { javach.close() } catch (e: NotImplementedException) { // ??? } ``` Soon after another `rebuildSelector0()`, Netty attempts to re-register channel, fails to do so (because it is already closed) and exits the infinite loop ``` WARN io.netty.channel.nio.NioEventLoop -- Selector.select() returned prematurely 512 times in a row; rebuilding Selector org.apache.plc4x.java.transport.serial.SerialPollingSelector@287d3f58. WARN io.netty.channel.nio.NioEventLoop -- Failed to re-register a Channel to the new Selector. java.nio.channels.ClosedChannelException: null at java.base/java.nio.channels.spi.AbstractSelectableChannel.register(AbstractSelectableChannel.java:222) at io.netty.channel.nio.NioEventLoop.rebuildSelector0(NioEventLoop.java:467) at io.netty.channel.nio.NioEventLoop.rebuildSelector(NioEventLoop.java:368) at io.netty.channel.nio.NioEventLoop.unexpectedSelectorWakeup(NioEventLoop.java:630) at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:578) at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) at java.base/java.lang.Thread.run(Thread.java:840) INFO io.netty.channel.nio.NioEventLoop -- Migrated 0 channel(s) to the new Selector. ``` ### Version v0.11.0 ### Programming Languages - [X] plc4j - [ ] plc4go - [ ] plc4c - [ ] plc4net ### Protocols - [ ] AB-Ethernet - [ ] ADS /AMS - [ ] BACnet/IP - [ ] CANopen - [ ] DeltaV - [ ] DF1 - [ ] EtherNet/IP - [ ] Firmata - [ ] KNXnet/IP - [ ] Modbus - [ ] OPC-UA - [ ] S7 -- 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: dev-unsubscr...@plc4x.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
