[英]Limiting rate of requests with Reactor
我正在使用项目反应器从使用休息的 Web 服务加载数据。 这是与多个线程并行完成的。 我开始达到 Web 服务的速率限制,因此我希望每秒最多发送 10 个请求以避免出现这些错误。 我将如何使用反应器做到这一点?
使用 zipWith(Mono.delayMillis(100))? 或者有什么更好的方法?
谢谢
您可以使用delayElements
而不是整个zipwith
。
下面的代码将以每秒 10 个请求的速率在https://www.google.com/
上执行GET
。 您必须进行其他更改,以支持您的服务器无法在 1 秒内处理所有 10 个请求的情况; 当您的服务器仍在处理前一秒询问的请求时,您可以跳过发送请求。
@Test
void parallelHttpRequests() {
// this is just for limiting the test running period otherwise you don't need it
int COUNT = 2;
// use whatever (blocking) http client you desire;
// when using e.g. WebClient (Spring, non blocking client)
// the example will slightly change for no longer use
// subscribeOn(Schedulers.elastic())
RestTemplate client = new RestTemplate();
var exit = new AtomicBoolean(false);
var lock = new ReentrantLock();
var condition = lock.newCondition();
MessageFormat message = new MessageFormat("#batch: {0}, #req: {1}, resultLength: {2}");
Flux.interval(Duration.ofSeconds(1L))
.take(COUNT) // this is just for limiting the test running period otherwise you don't need it
.doOnNext(batch -> debug("#batch", batch)) // just for debugging
.flatMap(batch -> Flux.range(1, 10) // 10 requests per 1 second
.flatMap(i -> Mono.fromSupplier(() ->
client.getForEntity("https://www.google.com/", String.class).getBody()) // your request goes here (1 of 10)
.map(s -> message.format(new Object[]{batch, i, s.length()})) // here the request's result will be the output of message.format(...)
.doOnSubscribe(s -> debug("doOnSubscribe: #batch = " + batch + ", i = " + i)) // just for debugging
.subscribeOn(Schedulers.elastic()) // one I/O thread per request
)
)
.subscribe(
s -> debug("received", s) // do something with the above request's result
e -> {
debug("error", e.getMessage());
signalAll(exit, condition, lock);
},
() -> {
debug("done");
signalAll(exit, condition, lock);
}
);
await(exit, condition, lock);
}
// most probably you won't need the "await" and "signalAll" methods below but
// I created them anyway just to be easier for one to run this in a test class
private void await(AtomicBoolean exit, Condition condition, Lock lock) {
lock.lock();
while (!exit.get()) {
try {
condition.await();
} catch (InterruptedException e) {
// maybe spurious wakeup
e.printStackTrace();
}
}
lock.unlock();
debug("exit");
}
private void signalAll(AtomicBoolean exit, Condition condition, Lock lock) {
exit.set(true);
try {
lock.lock();
condition.signalAll();
} finally {
lock.unlock();
}
}
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