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  1. Undertow
  2. UNDERTOW-2145

UndertowOutputStream and ServletOutputStreamImpl awaitWritable unnecessarily

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      After a channel.write(buffer), the implementation checks only buffer.hasRemaining, not the result of channel.write. We should write until a write returns zero. In synthetic benchmarks this seems to result in a significant performance improvement.

      UndertowOutputStream:
      https://github.com/undertow-io/undertow/blob/a3aebce60e57f83b02aa847c50d6e372b9a9b9b5/core/src/main/java/io/undertow/io/UndertowOutputStream.java#L294-L301

              while (buffer.hasRemaining()) {
            if(writeFinal) {
                channel.writeFinal(buffer);
            } else {
                channel.write(buffer);
            }
            if(buffer.hasRemaining()) {
                channel.awaitWritable();
            }
        }

      ServletOutputStreamImpl:
      https://github.com/undertow-io/undertow/blob/fde1ca6ffc8c6248a62179e98c59eb09202545c5/servlet/src/main/java/io/undertow/servlet/spec/ServletOutputStreamImpl.java#L581-L589

              while (buffer.hasRemaining()) {
            if (writeFinal) {
                channel.writeFinal(buffer);
            } else {
                channel.write(buffer);
            }
            if (buffer.hasRemaining()) {
                channel.awaitWritable();
            }
        }

       

            flaviarnn Flavia Rainone
            carterkozak Carter Kozak
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              Created:
              Updated:
              Resolved: