1. 问题
spring-cloud-gateway 作为统一的请求入口，负责转发请求到相应的微服务中去。
采用的 Spring Cloud 的版本为 Finchley SR2。
测试一个接口的性能，发现 tps 只有 1000 req/s 左右就上不去了。
[root@hystrix-dashboard wrk]# wrk -t 10 -c 200 -d 30s --latency -s post-test.lua 'http://10.201.0.28:8888/api/v1/json'
Running 30s test @ http://10.201.0.28:8888/api/v1/json
10 threads and 200 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 188.34ms 110.13ms 2.00s 78.43%
Req/Sec 106.95 37.19 333.00 77.38%
Latency Distribution
50% 165.43ms
75% 243.48ms
90% 319.47ms
99% 472.64ms
30717 requests in 30.04s, 7.00MB read
Socket errors: connect 0, read 0, write 0, timeout 75
Requests/sec: 1022.62
Transfer/sec: 238.68KB
其中 post-test.lua 内容如下：
request = function()
local headers = {}
headers["Content-Type"] = "application/json"
local body = [[{
"biz_code": "1109000001",
"channel": "7",
"param": {
"custom_id": "ABCD",
"type": "test",
"animals": ["cat", "dog", "lion"],
"retcode": "0"
}
}]]
return wrk.format('POST', nil, headers, body)
end
网关的逻辑是读取请求中 body 的值，根据 biz_code 字段去内存的路由表中匹配路由，然后转发请求到对应的微服务中去。
2. 排查
测试接口本身的性能：
[root@hystrix-dashboard wrk]# wrk -t 10 -c 200 -d 30s --latency -s post-test.lua 'http://10.201.0.32:8776/eeams-service/api/v1/json'
Running 30s test @ http://10.201.0.32:8776/eeams-service/api/v1/json
10 threads and 200 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 26.72ms 8.59ms 260.23ms 89.66%
Req/Sec 752.18 101.46 0.94k 78.67%
Latency Distribution
50% 23.52ms
75% 28.02ms
90% 35.58ms
99% 58.25ms
224693 requests in 30.02s, 50.83MB read
Requests/sec: 7483.88
Transfer/sec: 1.69MB
发现接口的 tps 可以达到 7000+。
通过 spring-boot-admin 查看网关的 cpu、内存等占用情况，发现都没有用满；查看线程状况，发现 reactor-http-nio 线程组存在阻塞情况。对于响应式编程来说，reactor-http-nio 线程出现阻塞结果是灾难性的。
通过 jstack 命令分析线程状态，定位阻塞的代码(第 19 行)：
"reactor-http-nio-4" #19 daemon prio=5 os_prio=0 tid=0x00007fb784d7f240 nid=0x80b waiting for monitor entry [0x00007fb71befc000]
java.lang.Thread.State: BLOCKED (on object monitor)
at java.lang.ClassLoader.loadClass(ClassLoader.java:404)
- waiting to lock <0x000000008b0cec30> (a java.lang.Object)
at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:93)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:282)
at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.registerWellKnownModulesIfAvailable(Jackson2ObjectMapperBuilder.java:753)
at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.configure(Jackson2ObjectMapperBuilder.java:624)
at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.build(Jackson2ObjectMapperBuilder.java:608)
at org.springframework.http.codec.json.Jackson2JsonEncoder.(Jackson2JsonEncoder.java:54)
at org.springframework.http.codec.support.AbstractCodecConfigurer$AbstractDefaultCodecs.getJackson2JsonEncoder(AbstractCodecConfigurer.java:177)
at org.springframework.http.codec.support.DefaultServerCodecConfigurer$ServerDefaultCodecsImpl.getSseEncoder(DefaultServerCodecConfigurer.java:99)
at org.springframework.http.codec.support.DefaultServerCodecConfigurer$ServerDefaultCodecsImpl.getObjectWriters(DefaultServerCodecConfigurer.java:90)
at org.springframework.http.codec.support.AbstractCodecConfigurer.getWriters(AbstractCodecConfigurer.java:121)
at org.springframework.http.codec.support.DefaultServerCodecConfigurer.getWriters(DefaultServerCodecConfigurer.java:39)
at org.springframework.web.reactive.function.server.DefaultHandlerStrategiesBuilder.build(DefaultHandlerStrategiesBuilder.java:103)
at org.springframework.web.reactive.function.server.HandlerStrategies.withDefaults(HandlerStrategies.java:90)
at org.springframework.cloud.gateway.support.DefaultServerRequest.(DefaultServerRequest.java:81)
at com.glsc.imf.dbg.route.RouteForJsonFilter.filter(RouteForJsonFilter.java:34)
at org.springframework.cloud.gateway.handler.FilteringWebHandler$DefaultGatewayFilterChain.lambda$filter$0(FilteringWebHandler.java:115)
at org.springframework.cloud.gateway.handler.FilteringWebHandler$DefaultGatewayFilterChain$$Lambda$800/1871561393.get(Unknown Source)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:44)
最终定位到问题代码为：
DefaultServerRequest req = new DefaultServerRequest(exchange); // 这行代码存在性能问题
return req.bodyToMono(JSONObject.class).flatMap(body -> {
...
});
这里的逻辑是我需要读取请求中 body 的值，并转化为 json，之后根据其中的特定字段去匹配路由，然后进行转发。这里选择了先把 exchange 转化为 DefaultServerRequest，目的是为了使用该类的 bodyToMono 方法，可以方便的进行转换。
3. 解决
改写代码以实现同样的功能：
return exchange.getRequest().getBody().collectList()
.map(dataBuffers -> {
ByteBuf byteBuf = Unpooled.buffer();
dataBuffers.forEach(buffer -> {
try {
byteBuf.writeBytes(IOUtils.toByteArray(buffer.asInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
});
return JSON.parseObject(new String(byteBuf.array()));
})
.flatMap(body -> {
...
});
之后进行测试，
[root@hystrix-dashboard wrk]# wrk -t 10 -c 200 -d 30s --latency -s post-test.lua 'http://10.201.0.28:8888/api/v1/json'
Running 30s test @ http://10.201.0.28:8888/api/v1/json
10 threads and 200 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 48.47ms 45.85ms 325.87ms 88.55%
Req/Sec 548.13 202.55 760.00 80.01%
Latency Distribution
50% 31.18ms
75% 39.44ms
90% 112.18ms
99% 227.19ms
157593 requests in 30.02s, 35.94MB read
Requests/sec: 5249.27
Transfer/sec: 1.20MB
发现 tps 从 1000 提升到了 5000+，问题解决。