From dcbbe94d4e9c0cab8848946797a916f4ae0bdc1d Mon Sep 17 00:00:00 2001 From: =?utf8?q?Alex=20R=C3=B8nne=20Petersen?= Date: Tue, 19 Sep 2017 20:32:26 +0200 Subject: [PATCH] [Mono.Profiler.Log] Fix excessive byte array allocations. The problem was that the base Stream.ReadByte () method allocates a temporary byte array and then calls Read (..., 1) on it. To solve this, we override ReadByte () in LogStream and use a private buffer to hold the result. It's a bit of a mystery to me why Stream.ReadByte () does it this way. The documentation for Stream explicitly says that instance methods aren't thread safe, so it would be perfectly fine for Stream.ReadByte () to do what we do here... --- .../Mono.Profiler.Log/Mono.Profiler.Log/LogStream.cs | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mcs/class/Mono.Profiler.Log/Mono.Profiler.Log/LogStream.cs b/mcs/class/Mono.Profiler.Log/Mono.Profiler.Log/LogStream.cs index 4fd0daf227d..b52402a91d4 100644 --- a/mcs/class/Mono.Profiler.Log/Mono.Profiler.Log/LogStream.cs +++ b/mcs/class/Mono.Profiler.Log/Mono.Profiler.Log/LogStream.cs @@ -26,6 +26,8 @@ namespace Mono.Profiler.Log { set => throw new NotSupportedException (); } + readonly byte[] _byteBuffer = new byte [1]; + public LogStream (Stream baseStream) { if (baseStream == null) @@ -48,6 +50,14 @@ namespace Mono.Profiler.Log { throw new NotSupportedException (); } + public override int ReadByte () + { + // The base method on Stream is extremely inefficient in that it + // allocates a 1-byte array for every call. Simply use a private + // buffer instead. + return Read (_byteBuffer, 0, sizeof (byte)) == 0 ? -1 : _byteBuffer [0]; + } + public override int Read (byte[] buffer, int offset, int count) { return BaseStream.Read (buffer, offset, count); -- 2.25.1