Connection warming¶

Connection warming since 1.2.0 keeps a small number of pre-connected, authenticated NNTP sockets standing by on each pooled provider. Playback and queue work borrow one instantly instead of paying the TCP + TLS + login handshake first — which is most of the wait between pressing play and the first bytes moving after an idle period.

How it works¶

Each pooled provider gets a warm floor: a target count of idle, ready-to-use connections. By default the floor is derived from the provider's Max Connections — roughly one sixth of it, at least 1 and at most 8.

flowchart TD
  pool["Warm floor: idle authenticated NNTP connections"]
  borrow["Playback / queue borrow"] -->|"no handshake wait"| pool
  sweep["Sweeper runs every idle-timeout / 2"] --> ping["DATE ping keeps warm sockets fresh"]
  ping -->|"stale socket"| refill["Dispose and refill floor"]
  refill --> pool
  sweep --> reap["Idle connections above the floor are reaped"]

• A background sweeper runs every half of the idle connection timeout (default: every 30 seconds). It refills the floor when sockets were lost and reaps idle connections only above the floor — warm connections are never closed just for being idle.
• Before a provider's own idle timeout can drop a warm socket, the sweeper pings it with a lightweight NNTP DATE command. A failed ping means the socket went stale; it is disposed and the floor refills.
• Warm connections never hold download permits, so the full configured connection width stays available to real work.
• If a provider is unreachable at startup, warming does not spin or block startup — retries resume once the provider circuit permits new opens. When InfiniDysk learns that a provider's real connection limit is lower than configured, the floor shrinks with it.
• Pending warm-up work has a 15-second acquisition budget and stops when its provider circuit trips. Factories already opening keep their own socket-open deadline. Warm-up never claims the half-open recovery probe. A connection-open timeout pauses new sockets without discarding healthy established ones; see provider acquisition waits.

What you see in the header¶

The Connections indicator in the top navigation shows pooled-provider totals, updated live (about five times per second):

• 5/50 — live connections across pooled providers versus their combined maximum.
• 2 active · 3 warm — connections currently transferring versus idle warm ones. The warm part only appears while at least one warm connection is standing by.
• Hovering explains: "Warm connections are pre-connected to your Usenet providers so playback can start faster."

Other states: a spinner with Connecting until the first update arrives, Reconnecting while the live UI connection recovers from a brief drop, and — / No providers when no Usenet provider is configured. The indicator is hidden on narrow screens. Backup-only providers are excluded from the totals.

Settings → Usenet shows the same live counts on each provider card.

Tuning¶

There is no settings-UI toggle; set the keys as headless environment variables (NZBDAV_CONFIG__USENET__WARM_CONNECTIONS__ENABLED / NZBDAV_CONFIG__USENET__WARM_CONNECTIONS__FLOOR). Changes take effect on the next provider save or restart — connection pools are not rebuilt when these keys change alone.

Read-start warm-up is enabled by default. Each newly opened WebDAV stream snapshots the value. Reads below 8 MiB, reads needing fewer than two connection batches, backup-only providers, and providers with an open circuit are skipped. The target is bounded by the stream's article window, download limit, provider connection limits, and any per-provider transfer cap. Opened sockets return to the normal idle pool; the warm floor still decides how many remain connected later. Set NZBDAV_CONFIG__USENET__READ_START_WARMUP__ENABLED=false and restart to restore demand-only expansion.

Cost and trade-offs¶

• Warm sockets are real connections and count against the provider plan's connection limit, even while idle.
• Read-start warm-up can create up to three TCP/TLS/AUTHINFO sessions at once. Turn it off if a provider rejects legal connection bursts.
• Keepalive traffic is negligible: one tiny DATE exchange per warm socket per sweep.
• On very small plans or memory-constrained hosts, lower the floor or disable warming entirely.

Usenet · NNTP pipelining · Streaming and seeking