### Sync/Async Replication

By default, replication is completed asynchronously. If synchronous replication is desired, set the --sync flag while adding a
remote replication target using the `mc admin bucket remote add` command. For mc releases on or after `RELEASE.2022-12-24T15-21-38Z`, the 

由於大部分的執行時間都消耗在等待 <abbr title="輸入與輸出">I/O</abbr> 操作上，因此這些操作被稱為 "I/O 密集型" 操作。

之所以稱為「非同步」，是因為電腦/程式不需要與那些耗時的任務「同步」，等待任務完成的精確時間，然後才能取得結果並繼續工作。

相反地，非同步系統在任務完成後，可以讓任務稍微等一下（幾微秒），等待電腦/程式完成手頭上的其他工作，然後再回來取得結果繼續進行。

相對於「非同步」（asynchronous），「同步」（synchronous）也常被稱作「順序性」（sequential），因為電腦/程式會依序執行所有步驟，即便這些步驟涉及等待，才會切換到其他任務。

### 並行與漢堡

上述非同步程式碼的概念有時也被稱為「並行」，它不同於「平行」。

並行和平行都與 "不同的事情或多或少同時發生" 有關。

但並行和平行之間的細節是完全不同的。

為了理解差異，請想像以下有關漢堡的故事：

=== ":material-language-kotlin: Kotlin"
    ```kotlin
      private val executor = Executors.newScheduledThreadPool(1)
      private val client = OkHttpClient()

    javaNetSocket.soTimeout = 0
    noNewExchanges()
  }

  override fun route(): Route = route

  override fun cancel() {
    // Close the raw socket so we don't end up doing synchronous I/O.
    rawSocket.closeQuietly()
  }

  override fun socket(): JavaNetSocket = javaNetSocket

  /** Returns true if this connection is ready to host new streams. */

  }

  @Test
  fun networkInterceptorThrowsRuntimeExceptionSynchronous() {
    interceptorThrowsRuntimeExceptionSynchronous(true)
  }

  /**
   * When an interceptor throws an unexpected exception, synchronous callers can catch it and deal
   * with it.
   */
  private fun interceptorThrowsRuntimeExceptionSynchronous(network: Boolean) {
    addInterceptor(network) { chain: Interceptor.Chain? -> throw RuntimeException("boom!") }

		// whether to replicate as the target could be temporarily down
		opts.TargetArn = tgtArn
		replicate := cfg.Replicate(opts)
		var synchronous bool
		if tgt != nil {
			synchronous = tgt.replicateSync
		}
		dsc.Set(newReplicateTargetDecision(tgtArn, replicate, synchronous))
	}
	return dsc
}

// Standard headers that needs to be extracted from User metadata.
var standardHeaders = []string{

    }

    /**
     * Returns the final value of the associated {@link ClosingFuture}, or throws an exception as
     * {@link Future#get()} would.
     *
     * <p>Because the asynchronous operation has already completed, this method is synchronous and
     * returns immediately.
     *
     * @throws CancellationException if the computation was cancelled
     * @throws ExecutionException if the computation threw an exception

            if (Thread.currentThread() == this.thread) {
                // we are in the transport thread, ie. on idle disconnecting
                // this is synchronous operation
                // This does not handle compound requests
                synchronized (this.inLock) {
                    final Long peekKey = peekKey();
                    if (peekKey == firstKey) {

It has an interesting, uncommon feature: using the same framework, it's possible to create APIs and also CLIs.

As it is based on the previous standard for synchronous Python web frameworks (WSGI), it can't handle Websockets and other things, although it still has high performance too.

/// info

    }

    /**
     * Returns the final value of the associated {@link ClosingFuture}, or throws an exception as
     * {@link Future#get()} would.
     *
     * <p>Because the asynchronous operation has already completed, this method is synchronous and
     * returns immediately.
     *
     * @throws CancellationException if the computation was cancelled
     * @throws ExecutionException if the computation threw an exception