a4af356075
The Read and Write methods of *tls.Conn call Handshake unconditionally, every time they are called, expecting it to only perform a new handshake if required. However in go 1.17 handshakeContext was extended to set up a cancelable Context, and importantly did so prior to checking if a handshake is required. This thus causes it to allocate on every call, even in those that are no-ops when called in a Read or Write on an established connection, sometimes leading to very large numbers of allocations during reads. This change adds an early return, prior to setting up the context or proceeding into the handshakeMutex and checking the handshake error, if the handshake status atomic indicates handshake is already complete. name old allocs/op new allocs/op delta Throughput/MaxPacket/1MB/TLSv12-10 1.07k ± 0% 0.62k ± 0% -42.16% (p=0.000 n=4+5) Throughput/MaxPacket/1MB/TLSv13-10 1.70k ± 0% 1.25k ± 0% ~ (p=0.079 n=4+5) Throughput/MaxPacket/2MB/TLSv12-10 1.62k ± 0% 0.73k ± 0% -55.18% (p=0.008 n=5+5) Throughput/MaxPacket/2MB/TLSv13-10 2.26k ± 0% 1.36k ± 0% -39.64% (p=0.008 n=5+5) Throughput/MaxPacket/4MB/TLSv12-10 2.74k ± 0% 0.95k ± 0% -65.35% (p=0.008 n=5+5) Throughput/MaxPacket/4MB/TLSv13-10 3.37k ± 0% 1.58k ± 0% -53.15% (p=0.008 n=5+5) Throughput/MaxPacket/8MB/TLSv12-10 4.96k ± 0% 1.39k ± 0% -72.06% (p=0.016 n=4+5) Throughput/MaxPacket/8MB/TLSv13-10 5.60k ± 0% 2.01k ± 0% -64.05% (p=0.008 n=5+5) Throughput/MaxPacket/16MB/TLSv12-10 9.42k ± 0% 2.27k ± 1% -75.92% (p=0.016 n=4+5) Throughput/MaxPacket/16MB/TLSv13-10 10.0k ± 0% 2.9k ± 0% -71.39% (p=0.008 n=5+5) Throughput/MaxPacket/32MB/TLSv12-10 18.3k ± 0% 4.0k ± 0% -77.97% (p=0.008 n=5+5) Throughput/MaxPacket/32MB/TLSv13-10 18.9k ± 0% 4.6k ± 0% -75.62% (p=0.008 n=5+5) Throughput/MaxPacket/64MB/TLSv12-10 36.2k ± 0% 7.5k ± 0% -79.15% (p=0.008 n=5+5) Throughput/MaxPacket/64MB/TLSv13-10 36.7k ± 0% 8.1k ± 0% -78.06% (p=0.008 n=5+5) Throughput/DynamicPacket/1MB/TLSv12-10 1.12k ± 0% 0.63k ± 0% -44.20% (p=0.008 n=5+5) Throughput/DynamicPacket/1MB/TLSv13-10 1.76k ± 0% 1.26k ± 0% -28.22% (p=0.016 n=5+4) Throughput/DynamicPacket/2MB/TLSv12-10 1.68k ± 0% 0.74k ± 0% -56.11% (p=0.008 n=5+5) Throughput/DynamicPacket/2MB/TLSv13-10 2.32k ± 0% 1.37k ± 0% -40.80% (p=0.008 n=5+5) Throughput/DynamicPacket/4MB/TLSv12-10 2.80k ± 0% 0.96k ± 0% -65.81% (p=0.008 n=5+5) Throughput/DynamicPacket/4MB/TLSv13-10 3.43k ± 0% 1.59k ± 0% -53.57% (p=0.008 n=5+5) Throughput/DynamicPacket/8MB/TLSv12-10 5.03k ± 0% 1.39k ± 0% -72.27% (p=0.008 n=5+5) Throughput/DynamicPacket/8MB/TLSv13-10 5.66k ± 0% 2.02k ± 0% -64.27% (p=0.008 n=5+5) Throughput/DynamicPacket/16MB/TLSv12-10 9.48k ± 0% 2.28k ± 1% -75.98% (p=0.008 n=5+5) Throughput/DynamicPacket/16MB/TLSv13-10 10.1k ± 0% 2.9k ± 0% -71.34% (p=0.008 n=5+5) Throughput/DynamicPacket/32MB/TLSv12-10 18.4k ± 0% 4.0k ± 0% -78.13% (p=0.008 n=5+5) Throughput/DynamicPacket/32MB/TLSv13-10 19.0k ± 0% 4.6k ± 0% -75.54% (p=0.008 n=5+5) Throughput/DynamicPacket/64MB/TLSv12-10 36.2k ± 0% 7.6k ± 1% -79.02% (p=0.008 n=5+5) Throughput/DynamicPacket/64MB/TLSv13-10 36.8k ± 0% 8.2k ± 1% -77.76% (p=0.008 n=5+5) Fixes #50657 Change-Id: Iacb1f9bf7802022960d9dbce141b8c0587a614d4 Reviewed-on: https://go-review.googlesource.com/c/go/+/379034 Reviewed-by: David Chase <drchase@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Filippo Valsorda <valsorda@google.com> Auto-Submit: Filippo Valsorda <filippo@golang.org> Run-TryBot: Filippo Valsorda <filippo@golang.org>
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