bitbake: bitbake-worker/runqueue: Avoid unnecessary bytes object copies

declaring queue=b"" creates an object of types bytes().
bytes() is an immutable object, and therefore doing "self.queue = self.queue + r"
creates a new object containing "self.queue" concatenated with "r".

On my test setup, we are passing 180MB of data of "workerdata" to the bitbake-worker,
so those copies significantly slow down the initialization of the bitbake-worker.

Rather use bytearray() which a mutable type, and use extend() to avoid copies.
In my test setup, byterray.extend() is 10.000 times faster than copying the queue,
for a queue size of 180MB.

(Bitbake rev: 2302b5316091dff189e6c3f546341b2274ed9d0a)

Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 7 insertions, 7 deletions

diff --git a/bitbake/bin/bitbake-worker b/bitbake/bin/bitbake-worker
index 451e6926bf..609e276fe2 100755
--- a/bitbake/bin/bitbake-worker
+++ b/bitbake/bin/bitbake-worker
@@ -91,19 +91,19 @@ def worker_fire_prepickled(event):
 worker_thread_exit = False
 
 def worker_flush(worker_queue):
-    worker_queue_int = b""
+    worker_queue_int = bytearray()
     global worker_pipe, worker_thread_exit
 
     while True:
         try:
-            worker_queue_int = worker_queue_int + worker_queue.get(True, 1)
+            worker_queue_int.extend(worker_queue.get(True, 1))
         except queue.Empty:
             pass
         while (worker_queue_int or not worker_queue.empty()):
             try:
                 (_, ready, _) = select.select([], [worker_pipe], [], 1)
                 if not worker_queue.empty():
-                    worker_queue_int = worker_queue_int + worker_queue.get()
+                    worker_queue_int.extend(worker_queue.get())
                 written = os.write(worker_pipe, worker_queue_int)
                 worker_queue_int = worker_queue_int[written:]
             except (IOError, OSError) as e:
@@ -346,12 +346,12 @@ class runQueueWorkerPipe():
         if pipeout:
             pipeout.close()
         bb.utils.nonblockingfd(self.input)
-        self.queue = b""
+        self.queue = bytearray()
 
     def read(self):
         start = len(self.queue)
         try:
-            self.queue = self.queue + (self.input.read(102400) or b"")
+            self.queue.extend(self.input.read(102400) or b"")
         except (OSError, IOError) as e:
             if e.errno != errno.EAGAIN:
                 raise
@@ -379,7 +379,7 @@ class BitbakeWorker(object):
     def __init__(self, din):
         self.input = din
         bb.utils.nonblockingfd(self.input)
-        self.queue = b""
+        self.queue = bytearray()
         self.cookercfg = None
         self.databuilder = None
         self.data = None
@@ -413,7 +413,7 @@ class BitbakeWorker(object):
                     if len(r) == 0:
                         # EOF on pipe, server must have terminated
                         self.sigterm_exception(signal.SIGTERM, None)
-                    self.queue = self.queue + r
+                    self.queue.extend(r)
                 except (OSError, IOError):
                     pass
             if len(self.queue):