Note what struct lines are packing/unpacking

dask · Apr 21, 2020 · c59f95d · c59f95d
1 parent 98d82dd
commit c59f95d
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/distributed/comm/ucx.py b/distributed/comm/ucx.py
@@ -190,7 +190,11 @@ async def write(
                 ]
 
                 # Send meta data
+
+                # Send # of frames (uint64)
                 await self.ep.send(struct.pack("Q", nframes))
+                # Send which frames are CUDA (bool) and
+                # how large each frame is (uint64)
                 await self.ep.send(
                     struct.pack(nframes * "?" + nframes * "Q", *cuda_frames, *sizes)
                 )
@@ -222,11 +226,15 @@ async def read(self, deserializers=("cuda", "dask", "pickle", "error")):
 
             try:
                 # Recv meta data
+
+                # Recv # of frames (uint64)
                 nframes_fmt = "Q"
                 nframes = host_array(struct.calcsize(nframes_fmt))
                 await self.ep.recv(nframes)
                 (nframes,) = struct.unpack(nframes_fmt, nframes)
 
+                # Recv which frames are CUDA (bool) and
+                # how large each frame is (uint64)
                 header_fmt = nframes * "?" + nframes * "Q"
                 header = host_array(struct.calcsize(header_fmt))
                 await self.ep.recv(header)