Make Windows process management nicer.

Subprocesses now get killed if the Bazel server itself is killed and so do their subprocesses.

Also implemented Subprocess#close() so that we get a little more control over when the native structures are cleaned up.

--
MOS_MIGRATED_REVID=126628000

3 files changed, 18 insertions, 4 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/shell/Command.java b/src/main/java/com/google/devtools/build/lib/shell/Command.java
index 35d3b8720e..8d40c15e24 100644
--- a/src/main/java/com/google/devtools/build/lib/shell/Command.java
+++ b/src/main/java/com/google/devtools/build/lib/shell/Command.java
@@ -817,10 +817,11 @@ public final class Command {
 
     log.finer("Waiting for process...");
 
-    TerminationStatus status =
-        waitForProcess(process, killSubprocessOnInterrupt);
-
+    TerminationStatus status = waitForProcess(process, killSubprocessOnInterrupt);
     observer.stopObserving(processKillable);
+    // #close() must be called after the #stopObserving() so that a badly-timed timeout does not
+    // try to destroy a process that is already closed
+    process.close();
 
     log.finer(status.toString());
 
diff --git a/src/main/java/com/google/devtools/build/lib/shell/JavaSubprocessFactory.java b/src/main/java/com/google/devtools/build/lib/shell/JavaSubprocessFactory.java
index ab3acd4e44..7c85cec5f9 100644
--- a/src/main/java/com/google/devtools/build/lib/shell/JavaSubprocessFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/shell/JavaSubprocessFactory.java
@@ -78,6 +78,11 @@ public class JavaSubprocessFactory implements Subprocess.Factory {
     public InputStream getInputStream() {
       return process.getInputStream();
     }
+
+    @Override
+    public void close() {
+      // java.lang.Process doesn't give us a way to clean things up other than #destroy()
+    }
   }
 
   public static final JavaSubprocessFactory INSTANCE = new JavaSubprocessFactory();
diff --git a/src/main/java/com/google/devtools/build/lib/shell/Subprocess.java b/src/main/java/com/google/devtools/build/lib/shell/Subprocess.java
index f8a8a553e7..e5710e7e7c 100644
--- a/src/main/java/com/google/devtools/build/lib/shell/Subprocess.java
+++ b/src/main/java/com/google/devtools/build/lib/shell/Subprocess.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.shell;
 
+import java.io.Closeable;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -21,7 +22,7 @@ import java.io.OutputStream;
 /**
  * A process started by Bazel.
  */
-public interface Subprocess {
+public interface Subprocess extends Closeable {
 
   /**
    * Something that can create subprocesses.
@@ -70,4 +71,11 @@ public interface Subprocess {
    * Returns a stream from which the stderr of the process can be read.
    */
   InputStream getErrorStream();
+
+  /*
+   * Terminates the process as thoroughly as the underlying implementation allows and releases
+   * native data structures associated with the process.
+   */
+  @Override
+  void close();
 }