enable pprof cpu profiling (#5081)

* enable pprof cpu profiling

This adds two routes to control pprof
Enable CPU profiling (100hz)
http://localhost:7280/pprof/start
Get the profile as flamegraph
http://localhost:7280/pprof/stop

The routes are behind the `pprof` feature flag

* switch to flamegraph endpoint

add safeguards
add query parameters
keep and return last flamegraph

quickwit/Cargo.toml

@@ -171,6 +171,7 @@ postcard = { version = "1.0.4", features = [
 ], default-features = false }
 predicates = "3"
 prettyplease = "0.2.0"
+pprof = { version = "0.13", features = ["flamegraph"] }
 proc-macro2 = "1.0.50"
 prometheus = { version = "0.13", features = ["process"] }
 proptest = "1"

quickwit/quickwit-cli/Cargo.toml

@@ -81,6 +81,7 @@ quickwit-storage = { workspace = true, features = ["testsuite"] }
 [features]
 jemalloc = ["dep:tikv-jemalloc-ctl", "dep:tikv-jemallocator"]
 ci-test = []
+pprof = ["quickwit-serve/pprof"]
 openssl-support = ["openssl-probe"]
 # Requires to enable tokio unstable via RUSTFLAGS="--cfg tokio_unstable"
 tokio-console = ["console-subscriber", "quickwit-common/named_tasks"]

quickwit/quickwit-serve/Cargo.toml

@@ -30,6 +30,7 @@ mime_guess = { workspace = true }
 once_cell = { workspace = true }
 opentelemetry = { workspace = true }
 percent-encoding = { workspace = true }
+pprof = { workspace = true, optional = true }
 prost = { workspace = true }
 prost-types = { workspace = true }
 regex = { workspace = true }
@@ -91,3 +92,9 @@ quickwit-opentelemetry = { workspace = true, features = ["testsuite"] }
 quickwit-proto = { workspace = true, features = ["testsuite"] }
 quickwit-search = { workspace = true, features = ["testsuite"] }
 quickwit-storage = { workspace = true, features = ["testsuite"] }
+
+[features]
+pprof = [
+  "dep:pprof"
+]
+

quickwit/quickwit-serve/src/lib.rs

@@ -38,6 +38,7 @@ mod metrics_api;
 mod node_info_handler;
 mod openapi;
 mod otlp_api;
+mod pprof;
 mod rate_modulator;
 mod rest;
 mod rest_api_response;