تجميع الاتصالات وإعادة استخدام القنوات

Opening a connection means a TCP handshake plus a TLS handshake — multiple round trips. Doing this per request destroys performance.

gRPC is built to reuse long-lived connections instead.

A gRPC channel wraps an HTTP/2 connection. HTTP/2 multiplexes many concurrent streams (RPCs) over a single connection, so one channel can serve thousands of calls.

The golden rule: create a channel once at startup and share it across your whole app. Never create a channel per request.

gRPC channels and the stubs built on them are safe for concurrent use. Many goroutines or threads can issue RPCs on the same client simultaneously.

HTTP/2 caps concurrent streams per connection (often around 100 via MAX_CONCURRENT_STREAMS). Beyond that, new RPCs queue. This is where pooling helps.

For very high concurrency, a single connection's stream limit becomes a bottleneck. A channel pool spreads load across several connections, multiplying available streams.

A simple pool keeps N channels and hands out the next one round-robin per call, balancing streams across connections.

Estimate pool size from concurrency: if you need 500 concurrent RPCs and each connection allows 100 streams, you need at least 5 connections plus headroom.

Idle connections can be dropped by load balancers or NATs. Configure keepalive pings so pooled channels stay healthy and reconnect transparently.

Channels report state: IDLE, CONNECTING, READY, TRANSIENT_FAILURE, SHUTDOWN. Monitoring these helps detect unhealthy pool members.

Common mistakes that kill performance:

• Dialing a new channel per request
• Closing and reopening channels needlessly
• Oversized pools wasting connections
• Ignoring keepalive, leading to stale connections

You learned channel reuse and pooling:

• Connections are expensive; reuse long-lived channels
• One channel multiplexes many streams and is thread-safe
• HTTP/2 caps concurrent streams per connection
• Channel pools spread load past that cap
• Use keepalive and monitor connection state