TiDB集群的duration突然升高，导致业务抖动
【TiDB 使用环境】生产环境
【TiDB 版本】7.5.6
【部署方式】云上部署（什么云）/机器部署
【操作系统/CPU 架构/芯片详情】
【机器部署详情】CPU大小/内存大小/磁盘大小
【集群数据量】
【集群节点数】
【问题复现路径】做过哪些操作出现的问题
【遇到的问题：问题现象及影响】
【资源配置】进入到 TiDB Dashboard -集群信息 (Cluster Info) -主机(Hosts) 截图此页面
【复制黏贴 ERROR 报错的日志】
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=10]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=7]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=7]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=8]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=8]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=7]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=9]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=9]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=10]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=10]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=11]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err
="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=8]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=7]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=9]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=9]
[2026/02/24 20:32:01.576 +08:00] [WARN] [write.rs:855] ["[store 3686910660] async write too slow, write_kv: 0s, write_raft: 6.610306337s, send: 0.000038747s, callback: 0s thread: sync-writer"] [takes=6610] [thread_id=142]
[2026/02/24 20:32:01.576 +08:00] [WARN] [store.rs:1162] ["[store 3686910660] handle 16 pending peers include 16 ready, 8 entries, 8 messages and 0 snapshots"] [takes=6610] [thread_id=142]
[2026/02/24 20:32:01.576 +08:00] [WARN] [pd.rs:2015] ["scheduling store_heartbeat timeout, force report store slow score to pd."] [store_id=3686910660] [thread_id=27]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=10]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=8]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=11]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=10]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=11]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=11]
[2026/02/24 20:32:01.576 +08:00] [WARN] [read_pool.rs:315] ["Already many pending tasks in the read queue, task is rejected"] [busy_err="reason: \"estimated wait time exceeds threshold\" estimated_wait_ms: 3480"] [busy_threshold=1s] [thread_id=9]
【其他附件：截图/日志/监控】
