I am working on a microservice which reads data from devices via tcp socket. Micro service will also serve on different servers. Therefore, a distributed structure was designed. A RMapCache has been created on redis so that devices can be regularly queried by different services. This Map keeps the current IP information of the devices on process. It is not desired to send more than one request to the same ip at the same time. The code of method that is created to add ip to this map is below. In that method redisson FairLock has been implemented to make the code block thread safe.
RMapCache<String, Long> ipMap=redissonClient.getMapCache("IPMAP");
RLock lock;
public synchronized boolean isIpToMap(String sIp, long timeout) {
lock=redissonClient.getFairLock("anyLock");
boolean res=false;
try {
res = lock.tryLock(6, 5, TimeUnit.SECONDS);
if(res) {
try {
return ipMap.fastPutIfAbsent(sIp, Calendar.getInstance().getTimeInMillis(), timeout, TimeUnit.SECONDS);
} catch (Exception e) {
e.printStackTrace();
}finally {
if (lock.isHeldByCurrentThread()) {
lock.unlock();
}
}
}
} catch (Exception e2) {
e2.printStackTrace();
}
return false;
}
However, when more than one service instance is run at the same time, an exception as below is thrown.
2021-09-24 18:19:45.242 ERROR 22080 --- [sson-netty-2-34] o.r.client.handler.CommandPubSubDecoder : Unable to decode data. channel: [id: 0x4f39d587, L:/10.10.8.3:54576 - R:192.168.100.96/192.168.100.96:6379], reply: ReplayingDecoderByteBuf(ridx=103, widx=103)
java.lang.NullPointerException: null
at org.redisson.client.handler.CommandPubSubDecoder.messageDecoder(CommandPubSubDecoder.java:212) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decodeList(CommandDecoder.java:416) [redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:377) [redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandPubSubDecoder.decodeCommand(CommandPubSubDecoder.java:71) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:134) [redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:91) [redisson-3.12.4.jar:3.12.4]
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489) [netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366) [netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265) [netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:646) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:581) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:498) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:460) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) [netty-common-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) [netty-common-4.1.27.Final.jar:4.1.27.Final]
at java.lang.Thread.run(Unknown Source) [na:1.8.0_211]
2021-09-24 18:19:45.253 WARN 22080 --- [sson-netty-2-34] io.netty.channel.DefaultChannelPipeline : An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
io.netty.handler.codec.DecoderException: java.lang.NullPointerException
at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:421) ~[netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265) ~[netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:646) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:581) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:498) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:460) [netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) [netty-common-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) [netty-common-4.1.27.Final.jar:4.1.27.Final]
at java.lang.Thread.run(Unknown Source) [na:1.8.0_211]
Caused by: java.lang.NullPointerException: null
at org.redisson.client.handler.CommandPubSubDecoder.messageDecoder(CommandPubSubDecoder.java:212) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decodeList(CommandDecoder.java:416) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:377) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandPubSubDecoder.decodeCommand(CommandPubSubDecoder.java:71) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:134) ~[redisson-3.12.4.jar:3.12.4]
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:91) ~[redisson-3.12.4.jar:3.12.4]
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489) ~[netty-codec-4.1.27.Final.jar:4.1.27.Final]
at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366) ~[netty-codec-4.1.27.Final.jar:4.1.27.Final]
... 28 common frames omitted
This issue was fixed in 3.13.4+ version.