Parallel downloading and writing to stdout

telecup_cli.py

@@ -221,18 +221,28 @@ async def download_part(client: TelegramClient, dest: typing.BinaryIO, dInfo: Do
     totalBytesDownloaded = 0
     lastRealTimeMeasurement = time.time()
 
+    buffer = None
+    currentLoop = asyncio.get_running_loop()
+    currentExecutor = ThreadPoolExecutor(max_workers=1)
+
+    def writeBuffer(buf):
+        if buf:
+            dest.write(buf)
+
     while totalBytesDownloaded < realSize:
         offset = totalBytesDownloaded
         limit = chunkSize
 
         try:
-            downloadResult: File = await client(GetFileRequest(
+            taskReceive = client(GetFileRequest(
                 inputFileLocation,
                 offset,
                 limit,
                 precise=False,
                 cdn_supported=False
             ))
+            taskWriteBuffer = currentLoop.run_in_executor(currentExecutor, writeBuffer, buffer)
+            downloadResult, writeResult = await asyncio.gather(taskReceive, taskWriteBuffer, loop=currentLoop, return_exceptions=False)
         except BadRequestError as e:
             if 'expire' in str(e.message).lower():
                 click.echo('Reloading message...', err=True)
@@ -249,7 +259,6 @@ async def download_part(client: TelegramClient, dest: typing.BinaryIO, dInfo: Do
             extraBytes = totalBytesDownloaded - realSize
             buffer = buffer[:-extraBytes]
 
-        dest.write(buffer)
         if totalBytesDownloaded % (pow(2, 20) * 10) == 0:
             click.echo(
                 f"{dInfo.part_info['part']}p {format_file_size(totalBytesDownloaded)}b {(time.time() - lastRealTimeMeasurement):.3f}s\t",