Re: [undertow-dev] output buffering

On Wed, Jun 17, 2020 at 1:02 AM Stuart Douglas <sdouglas(a)redhat.com&gt; wrote: > Is there a way I can know when the client has received all the data, even >> if it is buffered at the system level? >> > > If you call flush() on the OutputStream is won't return until the client > has recieved and acked the data AFAIK. > Alright, I tried this: System.out.println("start"); PooledByteBuffer poolBuffer = exchange.getConnection().getByteBufferPool().getArrayBackedPool().allocate(); byte[] buffer = poolBuffer.getBuffer().array(); // buffer.length is 16KB. exchange.startBlocking(); OutputStream output = exchange.getOutputStream(); try (var input = new FileInputStream(file)) { while (true) { int count = input.read(buffer); if (count == -1) break; output.flush(); // Before write() to avoid flushing a closed OutputStream. output.write(buffer, 0, count); } } exchange.endExchange(); System.out.println("end"); When I hit the URL, I see "start" and "end" printed immediately in the server log even though the curl download takes much, much longer at 10 bytes/sec. That was on Debian. Next I tried the same on Windows 10 and there I see only "start" while the download is in progress. That is true even if I remove the flush. So it seems it is something specific about Debian or its configuration. Any idea what is happening, or other ideas on how I can know when the client has really received the data? Cheers, -Nate