diff --git a/grpc-sys/build.rs b/grpc-sys/build.rs
index 832a3a38..dd99fecf 100644
--- a/grpc-sys/build.rs
+++ b/grpc-sys/build.rs
@@ -300,7 +300,7 @@ fn build_grpc(cc: &mut cc::Build, library: &str) {
 
 fn figure_systemd_path(build_dir: &str) {
     let path = format!("{build_dir}/CMakeCache.txt");
-    let f = BufReader::new(std::fs::File::open(&path).unwrap());
+    let f = BufReader::new(std::fs::File::open(path).unwrap());
     let mut libdir: Option<String> = None;
     let mut libname: Option<String> = None;
     for l in f.lines() {
diff --git a/src/env.rs b/src/env.rs
index 2c3f6c31..6a16aa04 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -5,6 +5,9 @@ use std::sync::mpsc;
 use std::sync::Arc;
 use std::thread::{Builder as ThreadBuilder, JoinHandle};
 
+use prometheus::local::LocalHistogram;
+use prometheus::IntCounter;
+
 use crate::cq::{CompletionQueue, CompletionQueueHandle, EventType, WorkQueue};
 use crate::grpc_sys;
 use crate::task::CallTag;
@@ -16,27 +19,30 @@ use {
         GRPC_TASK_WAIT_DURATION,
     },
     crate::task::resolve,
-    prometheus::{
-        core::{AtomicU64, Counter},
-        Histogram,
-    },
     std::time::Instant,
 };
 
+const METRICS_FLUSH_INTERVAL: u64 = 10_000; // 10s
+
 #[cfg(feature = "prometheus")]
 pub struct GRPCRunner {
-    cq_next_duration_his: Histogram,
-    execute_duration_his: Histogram,
-    wait_duration_his: Histogram,
-    event_counter: [Counter<AtomicU64>; 6],
+    cq_next_duration_his: LocalHistogram,
+    execute_duration_his: LocalHistogram,
+    wait_duration_his: LocalHistogram,
+    event_counter: [IntCounter; 6],
+    last_flush_time: Instant,
 }
 
 #[cfg(feature = "prometheus")]
 impl GRPCRunner {
     pub fn new(name: &String) -> GRPCRunner {
-        let cq_next_duration_his = GRPC_POOL_CQ_NEXT_DURATION.with_label_values(&[name]);
-        let execute_duration_his = GRPC_POOL_EXECUTE_DURATION.with_label_values(&[name]);
-        let wait_duration_his = GRPC_TASK_WAIT_DURATION.with_label_values(&[name]);
+        let cq_next_duration_his = GRPC_POOL_CQ_NEXT_DURATION
+            .with_label_values(&[name])
+            .local();
+        let execute_duration_his = GRPC_POOL_EXECUTE_DURATION
+            .with_label_values(&[name])
+            .local();
+        let wait_duration_his = GRPC_TASK_WAIT_DURATION.with_label_values(&[name]).local();
         let event_counter = ["batch", "request", "unary", "abort", "action", "spawn"]
             .map(|event| GRPC_POOL_EVENT_COUNT_VEC.with_label_values(&[name, event]));
         GRPCRunner {
@@ -44,11 +50,12 @@ impl GRPCRunner {
             execute_duration_his,
             wait_duration_his,
             event_counter,
+            last_flush_time: Instant::now(),
         }
     }
 
     // event loop
-    pub fn run(&self, tx: mpsc::Sender<CompletionQueue>) {
+    pub fn run(&mut self, tx: mpsc::Sender<CompletionQueue>) {
         let cq = Arc::new(CompletionQueueHandle::new());
         let worker_info = Arc::new(WorkQueue::new());
         let cq = CompletionQueue::new(cq, worker_info);
@@ -73,7 +80,21 @@ impl GRPCRunner {
             }
             self.execute_duration_his
                 .observe(now.elapsed().as_secs_f64());
+            self.maybe_flush();
+        }
+    }
+
+    fn maybe_flush(&mut self) {
+        let now = Instant::now();
+        if now.saturating_duration_since(self.last_flush_time)
+            < std::time::Duration::from_millis(METRICS_FLUSH_INTERVAL)
+        {
+            return;
         }
+        self.last_flush_time = now;
+        self.cq_next_duration_his.flush();
+        self.execute_duration_his.flush();
+        self.wait_duration_his.flush();
     }
 
     fn resolve(&self, tag: Box<CallTag>, cq: &CompletionQueue, success: bool) {
@@ -193,7 +214,7 @@ impl EnvBuilder {
                 .as_ref()
                 .map_or(format!("grpc-pool-{i}"), |prefix| format!("{prefix}-{i}"));
             #[cfg(feature = "prometheus")]
-            let runner = GRPCRunner::new(&name);
+            let mut runner = GRPCRunner::new(&name);
             builder = builder.name(name);
             let after_start = self.after_start.clone();
             let before_stop = self.before_stop.clone();
diff --git a/src/metrics.rs b/src/metrics.rs
index 690d0f64..8e1e9bed 100644
--- a/src/metrics.rs
+++ b/src/metrics.rs
@@ -29,7 +29,7 @@ lazy_static! {
         "grpc_pool_execute_duration",
         "Bucketed histogram of grpc pool execute duration for every time",
         &["name"],
-        exponential_buckets(1e-7, 2.0, 20).unwrap() // 100ns ~ 100ms
+        exponential_buckets(1e-7, 2.0, 30).unwrap() // 100ns ~ 100s
     )
     .unwrap();