ADDITIONAL SYSTEM INFORMATION :
Linux

A DESCRIPTION OF THE PROBLEM :
A write on a ChannelOutputStream, acquired via Files.newOutputStream, will race against a concurrent stream close() and easily bypass the expected delivery of ClosedChannelException (IOException), and instead throw a RuntimeException when FileChannelImpl created for the stream is closed asynchronously from another thread.

The RuntimeException is not expected (an IOException would be preferred)
FileChannelImpl's return of 0 for !isOpen() is unlikely to match with documentation indicating the FileChannel expected behavior, either for pre-write or in-progress write experiencing a close:
```
ClosedChannelException - If this channel is closed
AsynchronousCloseException - If another thread closes this channel while the write operation is in progress
```

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the provided reproducer

---------- BEGIN SOURCE ----------
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.channels.ClosedChannelException;

class closeForWrite {
  public static void main(String[] args) throws Exception {
    long occursIn = triggerRuntimeException();
    System.out.println(String.format("Occurs within %d close() calls", occursIn));
  }

  private static long triggerRuntimeException() {
    long attempts = 0;
    for (;;) {
      try {
        attempts++;
        attempt();
      } catch (ClosedChannelException e) {
        // ignore
      } catch (Exception e) {
        e.printStackTrace();
        return attempts;
      }
    }
  }

  private static void attempt() throws Exception {
    OutputStream out = Files.newOutputStream(Paths.get("testing"));
    Thread thread = new Thread(() -> {
      try {
        Thread.sleep(10);
        out.close();
      } catch (Exception e) {
        e.printStackTrace();
      }
    });
    thread.start();
    try {
      int b = 0;
      for (;;) {
        out.write(b);
      }
    } finally {
      thread.join();
    }
  }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
serializing writes with closes by stream would probably prevent this.

FREQUENCY :
OFTEN