线程池，CompletableFuture学习

   最近在做gRPC对服务端的压测，从开发身上学习到了高级用法,记录一下：

   简单说，就是长连接不释放导致TCP连接数耗尽，期望通过http2解决这个问题，也就是说，其实是用gRPC来重写了消息服务，因此需要高并发（并不是）及异步编程。

   开发review了我的代码以后，重写成这样了，记录在这里学习下。

   

CompletableFuture<?>[] completableFutures = new CompletableFuture[num];
ExecutorService executorService = Executors.newFixedThreadPool(200);
Stopwatch mainWatch = Stopwatch.createStarted();
for (int i = 0; i < num; i++) {
    completableFutures[i] = CompletableFuture.runAsync( () -> xxxxService.sendMessage("xielu_test")
            , executorService);
}
CompletableFuture.allOf(completableFutures).join();

   再来一版好了，双重异步！

   

public ListenableFuture<ReportResponse> sendMessage(String message) {
    ListeningExecutorService service = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(10));
    try {
        ListenableFuture<ReportResponse> responseFuture = messageReportStub.report(ReportRequest.newBuilder().setMessage(message).build());
        return responseFuture;
    } catch (final StatusRuntimeException e) {
        return null;
    }
}
-------------------------我是类的分割线-------------------------------------------------------------------------------------------------------

  

CompletableFuture completableFuture = new CompletableFuture();
ListenableFuture<ReportResponse>[] completableFutures = new ListenableFuture[num];
ListeningExecutorService executorService = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(100));
Stopwatch mainWatch = Stopwatch.createStarted();
for (int i = 0; i < num; i++) {
    completableFutures[i] = client.sendMessage("xielu_test");
}
Futures.addCallback(Futures.allAsList(completableFutures), new FutureCallback<List<ReportResponse>>() {
    @Override
    public void onSuccess(List<ReportResponse> reportResponses) {
        completableFuture.complete(reportResponses);
    }

    @Override
    public void onFailure(Throwable throwable) {
        completableFuture.completeExceptionally(throwable);
    }
}, executorService);
completableFuture.get();
long elapsed = mainWatch.elapsed(TimeUnit.MILLISECONDS);
String message = String.format("seed: %d, totalTime: %dms, tps: %d", num, elapsed, Math.round(num / (double) elapsed * 1000));