Allow manually specifying the number of threads

Author: denschub

Cargo.lock

@@ -4,7 +4,7 @@ description = "Receives syslog messages from nginx and stores them in a PostgreS
 authors = ["Dennis Schubert <[email protected]>"]
 repository = "https://github.com/denschub/nginx-syslog-postgresql-bridge"
 license = "MIT"
-version = "2.0.3"
+version = "2.1.0"
 edition = "2021"
 
 [profile.release]
@@ -14,7 +14,6 @@ lto = "fat"
 anyhow = "1"
 chrono = { version = "0.4", features = ["serde"] }
 clap = { version = "4", features = ["cargo", "derive", "env", "wrap_help"] }
-num_cpus = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 sqlx = { version = "0.8", features = [

Cargo.toml

@@ -1,3 +1,7 @@
+# 2.1.0
+
+This version introduces a new setting, `--threads`/`THREADS` that allows limiting the number of worker threads and the size of the database connection pool. If this flag is not set, the number of available CPU cores will be used, which matches the current behavior.
+
 # 2.0.3
 
 This version does not contain any functional changes. It only updates third-party dependencies.

Changelog.md

@@ -4,17 +4,30 @@ use sqlx::postgres::PgPoolOptions;
 
 use nginx_syslog_postgres_bridge::{Bridge, Settings};
 
-#[tokio::main]
-async fn main() -> Result<()> {
+fn main() -> Result<()> {
     let settings = Settings::parse();
+
+    let mut rt = tokio::runtime::Builder::new_multi_thread();
+    if let Some(threads) = settings.threads {
+        rt.worker_threads(threads);
+    }
+
+    rt.enable_all()
+        .build()?
+        .block_on(async { run(settings).await })
+}
+
+async fn run(settings: Settings) -> Result<()> {
     tracing_subscriber::fmt::init();
 
     let udp_socket = tokio::net::UdpSocket::bind(settings.listen_addr).await?;
     let db_pool = PgPoolOptions::new()
         .max_connections(
-            num_cpus::get()
+            tokio::runtime::Handle::current()
+                .metrics()
+                .num_workers()
                 .try_into()
-                .expect("number of CPU cores should fit into an u32"),
+                .expect("num_workers to be less than 2^32"),
         )
         .connect_with(settings.database_url)
         .await?;

src/main.rs

@@ -17,4 +17,8 @@ pub struct Settings {
     /// Maximum number of messages in the processing queue
     #[clap(long, short, env = "QUEUE_SIZE", default_value = "10000")]
     pub queue_size: usize,
+
+    /// Limits the number of threads used - defaults to the number of CPU cores
+    #[clap(long, env = "THREADS")]
+    pub threads: Option<usize>,
 }