发生错误时 Flux 间隔停止执行

Question

我正在使用Flux.interval来运行计划任务

 Flux
        .interval(Duration.ofSeconds(30))
        .doOnNext(duration -> log.info("Process has been started"))
        .flatMap(duration -> customService.process())
        .onErrorResume(throwable -> Flux.empty())
        .subscribe();

这里的事情是，如果在任何地方发生异常， onErrorResume已被调用，但调度程序停止工作 - 它不再调用customService.process()

我需要它每 30 秒继续调用一次方法，即使在任何地方有任何错误。 有人可以帮我吗？

Answer 1

在您的情况下.onErrorResume(throwable -> Flux.empty())只会在没有错误信号的情况下完成流程，但原始的Flux将被取消。

您有几种选择：

处理错误到位

在process级别处理错误。 在这种情况下，错误将被“忽略”并且初始Flux将继续。 从技术上讲，这与try-catch中的包装process方法相同，并且忽略命令式编程中的错误。

Flux.interval(Duration.ofSeconds(30))
    .doOnNext(i -> log.info("Process has been started: {}", i))
    .flatMap(i ->
            process(i)
                    .doOnError(e -> log.error("Error: {}", e.getMessage()))
                    .onErrorResume(e -> Mono.empty())
    );

Process has been started: 0
Process has been started: 1
Process has been started: 2
Process has been started: 3
Error: oops 3
Process has been started: 4
Process has been started: 5
Process has been started: 6
Process has been started: 7

重试

您可以在序列末尾使用.retry()运算符来重试任何错误，或者如果您需要更精细的控制，则可以使用.retryWhen 。

Flux.interval(Duration.ofSeconds(30))
        .doOnNext(i -> log.info("Process has been started: {}", i))
        .flatMap(i ->
                process(i)
        )
        .retry();

请注意，在这种情况下，每个错误都将触发对Flux.interval的重新订阅，并且序列将重新开始。

Process has been started: 0
Process has been started: 1
Process has been started: 2
Process has been started: 3
Error: oops 3
Process has been started: 0
Process has been started: 1
Process has been started: 2
Process has been started: 3