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 <Shruthi.Shruthi1@ibm.com>

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

@@ -23,6 +23,11 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2022, 2022 All Rights Reserved
+ * ===========================================================================
+ */
 package sun.nio.ch;
 
 import java.io.FileDescriptor;
@@ -107,8 +112,8 @@ 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) {