gRPC Trace Flags ---------------- The `GRPC_TRACE` environment variable supports a comma-separated list of tracer names or glob patterns that provide additional insight into how gRPC C core is processing requests via debug logs. Available tracers include: - api - API calls to the C core. - backend_metric - C++ backend metric recorder APIs. - backend_metric_filter - Filter that populates backend metric data in server trailing metadata. - bdp_estimator - Behavior of bdp estimation logic. - call - Traces operations on a call through the gRPC stack. - call_error - Possible errors contributing to final call statuses. - cares_address_sorting - Operations of the c-ares based DNS resolver's address sorter. - cares_resolver - Operations of the c-ares based DNS resolver. - cds_lb - CDS LB policy. - channel - Operations on the C core channel stack. - channel_stack - Construction of the set of filters in a channel stack. - chaotic_good - Chaotic good transport. - chttp2_hpack_parser - HTTP/2 HPACK parser. - chttp2_new_stream - HTTP/2 incoming stream creation. - client_channel - Client channel control plane activity, including resolver and load balancing policy interaction. - client_channel_call - Client channel call activity related to name resolution. - client_channel_lb_call - Client channel call activity related to load balancing picking. - client_idle_filter - Client idleness filter. - compression - Compression operations. - connectivity_state - Connectivity state changes to channels. - cronet - Cronet transport engine. - dns_resolver - The active DNS resolver. - environment_autodetect - GCP environment auto-detection. - event_engine - High-level EventEngine operations. - event_engine_client_channel_resolver - EventEngine-based client channel resolver state and events. - event_engine_dns - EventEngine DNS resolver. - event_engine_endpoint - EventEngine Endpoint operations. - event_engine_endpoint_data - Detailed dump of EventEngine endpoint TCP data. - event_engine_poller - EventEngine Poller events. - executor - gRPC's legacy thread pool ('the executor'). - fault_injection_filter - Fault injection. - flowctl - Http2 flow control. - fork - Fork support. - glb - gRPClb load balancer. - grpc_authz_api - gRPC authorization. - handshaker - Handshaking state. - health_check_client - Health checking client code. - http - Http2 transport engine. - http1 - HTTP/1.x operations performed by gRPC. - http2_ping - Pings/ping acks/antagonist writes in http2 stack. - http2_stream_state - Http2 stream state mutations. - http_keepalive - gRPC keepalive pings. - inproc - In-process transport. - metadata_query - GCP metadata queries. - op_failure - Error information when failure is pushed onto a completion queue. The `api` tracer must be enabled for this flag to have any effect. - orca_client - Out-of-band backend metric reporting client. - outlier_detection_lb - Outlier detection. - pick_first - Pick first load balancing policy. - plugin_credentials - Plugin credentials. - priority_lb - Priority LB policy. - queue_pluck - Completion queue plucking. The `api` tracer must be enabled for this flag to have any effect. - resource_quota - Resource quota objects internals. - retry - Call retries. - ring_hash_lb - Ring hash load balancing policy. - rls_lb - RLS load balancing policy. - round_robin - Round robin load balancing policy. - secure_endpoint - Bytes flowing through encrypted channels. - server_channel - Lightweight trace of significant server channel events. - stateful_session_filter - Stateful session affinity. - subchannel - Connectivity state of subchannels. - subchannel_pool - Subchannel pool. - tcp - Bytes in and out of a channel. - timer - Timers (alarms) in the grpc internals. - timer_check - more detailed trace of timer logic in grpc internals. - tsi - TSI transport security. - weighted_round_robin_lb - Weighted round robin load balancing policy. - weighted_target_lb - Weighted target LB policy. - xds_client - XDS client. - xds_client_refcount - Refcount of XDS client. - xds_cluster_impl_lb - XDS Cluster impl LB policy. - xds_cluster_manager_lb - XDS Cluster manager LB policy. - xds_override_host_lb - XDS Override host LB. - xds_resolver - XDS Resolver. - xds_server_config_fetcher - XDS Server config fetcher. - xds_wrr_locality_lb - XDS WRR locality LB policy. The following tracers will only run in binaries built in DEBUG mode. This is accomplished by invoking `bazel build --config=dbg ` - auth_context_refcount - Auth context refcounting. - call_combiner - Call combiner state. - call_refcount - Refcount on call. - call_state - Traces transitions through the call spine state machine. - closure - Legacy closure creation, scheduling, and completion. - combiner - Combiner lock state. - cq_refcount - Completion queue refcounting. - error_refcount - Error refcounting. - fd_refcount - File descriptor refcounting. - fd_trace - Legacy file descriptor create(), shutdown() and close() calls for channel fds. - lb_policy_refcount - LB policy refcounting. - party_state - Coordination of activities related to a call. - pending_tags - Still-in-progress tags on completion queues. The `api` tracer must be enabled for this flag to have any effect. - polling - The active polling engine. - polling_api - API calls to polling engine. - promise_primitives - Low-level primitives in the promise library. - resolver_refcount - Resolver refcouting. - security_connector_refcount - Refcounting for security connectors (part of channel credentials). - slice_refcount - Slice refcounting. - stream_refcount - Stream refcounting. - subchannel_refcount - Subchannel refcounting. - work_serializer - A synchronization mechanism used to ensure that only one thread is executing at a given time. Glob patterns and special cases: - `*` can be used to turn all traces on. - Individual traces can be disabled by prefixing them with `-`. - `*refcount*` will turn on all of the tracers for refcount debugging. - if `list_tracers` is present, then all of the available tracers will be printed when the program starts up. Example: export GRPC_TRACE=*,-pending_tags