Hang in PreClose method during dup2 system call

During fcntl, dup2 system calls if read/write happens then PreClose method gets hang. This issue is not seen if we Signal/Kill the thread first and then call the preClose method.

Signed-off-by: Shruthi.Shruthi1 <[email protected]>

Author: shruacha1234

src/java.base/unix/classes/sun/nio/ch/SourceChannelImpl.java

@@ -107,8 +107,8 @@ protected void implCloseSelectableChannel() throws IOException {
                 assert state == ST_CLOSING;
                 long th = thread;
                 if (th != 0) {
-                    nd.preClose(fd);
                     NativeThread.signal(th);
+                    nd.preClose(fd);
 
                     // wait for read operation to end
                     while (thread != 0) {