Allow concurrent tools/java_heap_dump.

Change-Id: Ib3456499ce36b508ed1d2a12c66006e283928ac1
diff --git a/tools/java_heap_dump b/tools/java_heap_dump
index 03abb01..7fc8540 100755
--- a/tools/java_heap_dump
+++ b/tools/java_heap_dump
@@ -24,6 +24,7 @@
 import sys
 import tempfile
 import time
+import uuid
 
 NULL = open(os.devnull)
 
@@ -61,9 +62,11 @@
       }}
 """
 
+UUID = str(uuid.uuid4())[-6:]
+PROFILE_PATH = '/data/misc/perfetto-traces/java-profile-' +  UUID
+
 PERFETTO_CMD = ('CFG=\'{cfg}\'; echo ${{CFG}} | '
-                'perfetto --txt -c - -o '
-                '/data/misc/perfetto-traces/java-profile-{user} -d')
+                'perfetto --txt -c - -o ' + PROFILE_PATH + ' -d')
 
 
 def main(argv):
@@ -189,8 +192,10 @@
     time.sleep(1)
 
   subprocess.check_call(
-    ['adb', 'pull', '/data/misc/perfetto-traces/java-profile-{}'.format(user),
-     output_file], stdout=NULL)
+    ['adb', 'pull', PROFILE_PATH, output_file], stdout=NULL)
+
+  subprocess.check_call(
+        ['adb', 'shell', 'rm', PROFILE_PATH], stdout=NULL)
 
   print("Wrote profile to {}".format(output_file))
   print("This can be viewed using https://ui.perfetto.dev.")