fix: raise default ZO_ALERT_SCHEDULE_CONCURRENCY to 50 (#15869)

src/config/src/config.rs

@@ -665,6 +665,7 @@ pub fn load_config() -> Result<(), anyhow::Error> {
 }
 static CHROME_LAUNCHER_OPTIONS: tokio::sync::OnceCell<Option<BrowserConfig>> =
     tokio::sync::OnceCell::const_new();
+static CHROME_SEMAPHORE: std::sync::OnceLock<tokio::sync::Semaphore> = std::sync::OnceLock::new();
 
 pub async fn get_chrome_launch_options() -> &'static Option<BrowserConfig> {
     CHROME_LAUNCHER_OPTIONS
@@ -672,6 +673,16 @@ pub async fn get_chrome_launch_options() -> &'static Option<BrowserConfig> {
         .await
 }
 
+/// Caps concurrent headless Chrome processes at the CPU limit; hold a permit while one runs.
+pub fn chrome_semaphore() -> &'static tokio::sync::Semaphore {
+    CHROME_SEMAPHORE.get_or_init(|| {
+        let cfg = get_config();
+        // cpu_num is floored at 2 and real_cpu_num ignores the memory limit, so take the smaller.
+        let permits = cfg.limit.cpu_num.min(cfg.limit.real_cpu_num);
+        tokio::sync::Semaphore::new(max(1, permits))
+    })
+}
+
 async fn init_chrome_launch_options() -> Option<BrowserConfig> {
     let cfg = get_config();
     if !cfg.chrome.chrome_enabled || !cfg.common.report_server_url.is_empty() {
@@ -2746,7 +2757,7 @@ pub struct Limit {
         help = "Count-based alerts whose row sentinel exceeds this switch to a COUNT(*) decision query plus a 100-row payload sample (alerts_2.md 4.4c). Clamped up to the 100-row floor."
     )]
     pub alert_hybrid_count_threshold: i64,
-    #[env_config(name = "ZO_ALERT_SCHEDULE_CONCURRENCY", default = 5)]
+    #[env_config(name = "ZO_ALERT_SCHEDULE_CONCURRENCY", default = 50)]
     pub alert_schedule_concurrency: i64,
     #[env_config(
         name = "ZO_ALERT_MAX_GROUPS",
@@ -6608,4 +6619,13 @@ mod tests {
         assert_eq!(select_ext_auth_salt("", "stored"), "stored");
         assert_eq!(select_ext_auth_salt("", ""), LEGACY_EXT_AUTH_SALT);
     }
+
+    #[test]
+    fn test_chrome_semaphore_never_exceeds_cpu_limit() {
+        let cfg = get_config();
+        let permits = chrome_semaphore().available_permits();
+        assert!(permits >= 1);
+        assert!(permits <= cfg.limit.real_cpu_num);
+        assert!(permits <= cfg.limit.cpu_num);
+    }
 }

src/core/src/dashboards/reports.rs

@@ -886,6 +886,9 @@ pub enum GenerateReportError {
     #[error(transparent)]
     JoinHandlerError(#[from] tokio::task::JoinError),
 
+    #[error(transparent)]
+    ChromeSemaphoreError(#[from] tokio::sync::AcquireError),
+
     #[error("[REPORT] main element not rendered yet for dashboard {dashboard_id}: {e}")]
     MainElementNotRendered {
         dashboard_id: String,
@@ -941,6 +944,7 @@ async fn generate_report(
         );
     }
 
+    let _chrome_permit = config::chrome_semaphore().acquire().await?;
     log::info!("launching browser for dashboard {dashboard_id}");
     let (mut browser, mut handler) =
         Browser::launch(get_chrome_launch_options().await.as_ref().unwrap().clone()).await?;

src/report_server/src/report.rs

@@ -168,6 +168,7 @@ pub async fn generate_report(
     // Only one tab is supported for now
     let tab_id = &dashboard.tabs[0];
 
+    let _chrome_permit = config::chrome_semaphore().acquire().await?;
     log::info!("launching browser for dashboard {dashboard_id}");
     let browser_config = get_chrome_launch_options()
         .await