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New configuration options

• proxy.config.http.origin_max_connections_queue limits the number of requests to be queued when the proxy.config.http.origin_max_connections is reached.
• Two new timeouts are available for WebSockets: proxy.config.websocket.no_activity_timeout and proxy.config.websocket.active_timeout.
• The congestion control algorithm used is now configurable for both incoming, and outbound connections, via proxy.config.net.tcp_congestion_control_in and proxy.config.net.tcp_congestion_control_out.

Jira: TS-4341, TS-3922, TS-4064, 

TLS

 We continue to improve our TLS (HTTPS) features and support. Noteworthy in 5.2.x is:

• SSLv3 is now disabled by default!
• Dynamic TLS record size tuning. According to Ilya, this makes us the first server that is all Green. 
• Add forward secrecy support with DHE.
• Add ssl_pre_handshake hook for better plugin access to SSL handling.
• Improved session cache, for better performance and scalability.
• New configuration for OpenSSL session cache, proxy.config.ssl.session_cache.auto_clear.

Jira: TS-3153, TS-2503, TS-2417, TS-2956, TS-3080, TS-3127

traffic_line

• traffic_line -m is now using an unachored regular expression, similar to how diagnostic tracers work.
• traffic_line --backtrace will produce a stack backtrace for all running threads.

Jira: TS-3034, TS-3145

traffic_layout

A new command line utility, traffic_layout, is now available. This will show the layout and configuration option for the ATS build tree.

Jira: TS-3041

traffic_via

This is a new command line tool, to parse and decipher the Via: header that Traffic Server can produce. This is useful for debugging e.g. cache results etc.

Jira: TS-3149

traffic_crashlog

This is the helper application around the new crash logging feature. For more information, see the documentation.

• In preparation for the new Lua metrics module in v7.0.0, you can enable this feature in v6.2.x with proxy.config.stats.enable_lua.
• An experimental implementation of H2 streams priorities can be enabled with proxy.config.http2.stream_priority_enabled.
• We now provide better control over various H2 (HTTP/2) features, including proxy.config.http2.min_concurrent_streams_in, proxy.config.http2.max_active_streams_in and proxy.config.http2.active_timeout_in.

Jira: TS-4341, TS-3922, TS-4064, TS-4099

TLS

 We continue to improve our TLS (HTTPS) features and support. Noteworthy in 6.2.x is:

Jira: Jira: TS-3195

Plugin Improvements

The following plugins have new features and improvements.

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Jira: TS-2955, TS-3108, TS-3068

stats_over_http

This plugin will now emit JSON numbers.

Jira: TS-3071

background_fetch

• The plugin behavior and activation can now be controlled per remap-rule.
• You an control the behavior based on content type.

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