How can I use bulkhead in feignClient? - hystrix

Question

1、Can I use bulkhead pattern in feignClient?
2、I have some confusion about hystrix.
For example，if I only have three feign clients "a","b","c"。The "a" calls "b" and "c".
I know I can easily use circuit breaker with fallback parameter and some Configuration like this:
#FeignClient(name = "b", fallback = bFallback.class)
protected interface HystrixClient {
//some methods
}
#FeignClient(name = "c", fallback = cFallback.class)
protected interface HystrixClient {
//some methods
}
In another way,I could use #HystrixCommand to wrap my remote call with some Configuration like this:
#HystrixCommand(fallbackMethod="getFallback")
public Object get(#PathVariable("id") long id) {
//...
}
In addition I can configure some parameter in #HystrixCommand or application.yml,and I also can add threadPoolKey in in #HystrixCommand
Q1:I have learn that Hystrix wrapped remote call to achieve purpose，I can understand on the latter way，but the former way likes wrapping callee?
I found in document that:
Feign will wrap all methods with a circuit break
Is this mean FeignClient seems adding #Hystrixcommand on every method in interface in essence?
Q2:If the Feign client "b" have three remote call,how can I let them run in bulkhead to avoid one method consuming all thread？ to Combine the feignClient and #HystrixCommand? will them conflict？
Because I do not found the parameter likes threadPoolKey in feignClient. Auto bulkhead?
Q3:If my hystrix configuration is in application.yml ,the feignClient pattern and #HytirxCommand pattern whether have the same configuration pattern？ like this:
hystrix:
command：
　default:
execution:
isolation:
thread:
timeoutInMilliseconds:1000
circuitBreaker:
requestVolumeThreshold:10
...
...
but what's the follow Timeout?
feign:
client:
config:
feignName:
connectTimeout: 5000
readTimeout: 5000

Answer 1

1、Can I use bulkhead pattern in feignClient?
Java doc of setterFactory() method of HystrixFeign class says:
/**
* Allows you to override hystrix properties such as thread pools and command keys.
*/
public Builder setterFactory(SetterFactory setterFactory) {
this.setterFactory = setterFactory;
return this;
}
https://cloud.spring.io/spring-cloud-netflix/multi/multi_spring-cloud-feign.html says:
Spring Cloud Netflix does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:
• Logger.Level
• Retryer
• ErrorDecoder
• Request.Options
• Collection
• SetterFactory
So we should create setterFactory and specifying thread pool there. You can create a Bean like this:
#Bean
public SetterFactory feignHystrixSetterFactory() {
return (target, method) -> {
String groupKey = target.name();
String commandKey = Feign.configKey(target.type(), method);
return HystrixCommand.Setter
.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey))
.andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey( target.type().getSimpleName() ));
};
}
but what's the follow Timeout?
Feign client timeout is similar to ribbon timeout and specifies the properties of httpconnectin but you can define different timeouts for different feignclient.
feign.client.config.bar.readTimeout //this configuration will apply to bar client
feign.client.config.default.readTimeout // this configuration will apply to all feign
How did I found that? if you debug your application and put breakpoints on the following code of RetryableFeignLoadBalancer class:
final Request.Options options;
if (configOverride != null) {
RibbonProperties ribbon = RibbonProperties.from(configOverride);
options = new Request.Options(ribbon.connectTimeout(this.connectTimeout),
ribbon.readTimeout(this.readTimeout));
}
else {
options = new Request.Options(this.connectTimeout, this.readTimeout);
}
you will see these value will be used as properties of HTTPConection.pls have a look at feign.Client class.
connection.setConnectTimeout(options.connectTimeoutMillis());
connection.setReadTimeout(options.readTimeoutMillis());