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Don't be overly aggressive on stream failures and closing #6525

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Merged
zwoop merged 1 commit into from
Apr 7, 2020
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Don't be overly aggressive on stream failures and closing #6525

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4 changes: 2 additions & 2 deletions proxy/http2/Http2ClientSession.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -610,8 +610,8 @@ Http2ClientSession::state_process_frame_read(int event, VIO *vio, bool inside_fr
ip_port_text_buffer ipb;
const char *client_ip = ats_ip_ntop(get_client_addr(), ipb, sizeof(ipb));
Warning("HTTP/2 session error client_ip=%s session_id=%" PRId64
" closing a connection, because its stream error rate (%f) is too high",
client_ip, connection_id(), this->connection_state.get_stream_error_rate());
" closing a connection, because its stream error rate (%f) exceeded the threshold (%f)",
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@zwoop zwoop Mar 17, 2020 •
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This was only done to make the Warning() consistent with the other two places we do this check.

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@maskit maskit Mar 18, 2020

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Adding configured threshold value is fine, but removing "too high" would make it hard to see whether the close was graceful or immediate.

client_ip, connection_id(), this->connection_state.get_stream_error_rate(), Http2::stream_error_rate_threshold);
err = Http2ErrorCode::HTTP2_ERROR_ENHANCE_YOUR_CALM;
}

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3 changes: 2 additions & 1 deletion proxy/http2/Http2ConnectionState.h
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Expand Up @@ -250,7 +250,8 @@ class Http2ConnectionState : public Continuation
get_stream_error_rate() const
{
int total = get_stream_requests();
if (total > 0) {

if (total >= (1 / Http2::stream_error_rate_threshold)) {
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@zwoop zwoop Mar 17, 2020

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The point of this is to require a minimum number of samples before we can calculate a reasonably trustworthy rate of failures. The smaller the threshold, the more samples needed. Probably not statistically safe, but this at least avoids the issues where if (in the default configs) any of the first 10 streams has an error, it's enough to close the connection.

return (double)stream_error_count / (double)total;
} else {
return 0;
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