Hash sum → 3e248df4855d8f97071ef20c4c5d7b29|
|
Adobe Premiere Pro allows video editing and content creation. It equips users with timeline editing, color correction, audio mixing, and effects. Supports many formats and Adobe Creative Cloud integration. Adopted by filmmakers, editors, and content creators. Known for flexibility, power, and intuitive interface. Leading choice in video production.
Updated on: 2026-05-09|
|
Ableton Live provides tools for making and playing music. It supports recording, sequencing, mixing, and arranging processes. It features session and arrangement perspectives for flexible production. It offers built-in instruments, effects, and sound samples. It accommodates plugins and advanced automation functionalities. Designed for music producers, DJs, and performing artists. Distinguished by its intuitive design and real-time features.
Hash Value:e26430fdb2323376f2354a700d10cff8
Update: 2026-05-12|
|
Ableton Live is a software used for producing and performing music. The software offers recording, sequencing, mixing, and arranging capabilities. It supports session and arrangement views to provide workflow flexibility. It includes a range of instruments, effects, and sample sounds. It allows integration of plugins and advanced automation tools. Suitable for producers, DJs, and performers alike. Famous for a user-friendly interface and real-time functionality.
SHA sum:|
|
Minimal application that provides users with a simple means of monitoring how their computer is used while they are away, and comes packed with a stealth mode. LightLogger Keylogger is a monitoring software solution that can record typed keystrokes, visited websites, Clipboard content, loaded programs and take snapshots of computer activity at a given interval.
Hash-sum: 23bff30633ffe8ce5a61af84fb440f88
Last update: 2026-05-10|
|
Enjoy your favorite videos without having to stream by easily downloading them with the help of this practical and intuitive software application. When I want to grab a video from various platforms, I can do so with the Save as option. Then again, I’m sure you noticed that you can’t do that with all websites. Even on YouTube, you probably noticed that not all clips have the download button available.
很多 DBA 第一次遇到这种场景时,会本能地把目光聚焦在 “cursor: pin S wait on X”,因为它出现的会话最多、最显眼。但 ASH 的阻塞链(Blocking Session Tree)告诉我们:所有 pin S 会话都只是“受害者”,真正的罪魁祸首是 library cache lock。于是问题被拆成两步:
一、时间点回溯 通过 DBA_HIST_ACTIVE_SESS_HISTORY 定位第一条 library cache lock 的记录:
TIME EVENT SESSION_ID BLOCKING_SESSION
22:00:33 library cache lock 1723 1349
也就是说,故障根因从 22:00:33 就已埋下。
二、阻塞链逐级展开 SESSION 1723 • 执行的模块:DBMS_STATS(自动统计信息收集作业) • 状态:持续处于 library cache lock,并被 1349 阻塞
SESSION 1349 • 执行的模块:Auto SQL Tuning Task(SYS_AUTO_SQL_TUNING_TASK) • 当前等待:db file parallel read(在做 I/O) • 状态:未被任何其他会话阻塞,处于“链头”位置
至此,链路清晰: Auto SQL Tuning Task(1349) → library cache lock → DBMS_STATS(1723) → cursor: pin S wait on X(大量应用会话)
三、为什么 Auto SQL Tuning 会锁 Library Cache? Auto SQL Tuning 在创建/删除 SQL Profile、Index 或 SQL Patch 时,需要对相关 cursor 加排他型 Library Cache Lock(mode 3)。而 22:00 又是默认的维护窗口,两个自动任务正好撞车:
四、如何避免重演 Auto SQL Tuning 与 Auto Space Advisor 默认在夜间维护窗口并行跑,对 I/O、Library Cache、Latch 都有潜在冲击。对于 OLTP 核心库,常见做法是“关掉再说”:
— 关闭 Auto SQL Tuning BEGIN DBMS_AUTO_TASK_ADMIN.DISABLE( client_name => ‘sql tuning advisor’, operation => NULL, window_name => NULL); END; /
— 关闭 Auto Space Advisor BEGIN DBMS_AUTO_TASK_ADMIN.DISABLE( client_name => ‘auto space advisor’, operation => NULL, window_name => NULL); END; /
关闭后,如果仍有统计信息收集需求,可以:
五、小结 • “cursor: pin S wait on X” 只是表象,真正的根因往往在更高层级的 Library Cache Lock。 • ASH 的 Blocking Session Tree 是定位连锁等待的最快路径。 • Oracle 的自动任务(Auto SQL Tuning、Auto Space Advisor、Auto Stats)在维护窗口内可能互相阻塞;对高并发 OLTP 系统,建议关闭或错峰。
希望这篇踩坑记录能帮到你。如果你也曾被深夜的 Library Cache Lock 折磨过,欢迎留言交流更多“救火”姿势。
]]>在生产环境中,我们经常会看到 AWR/ASH 中高居榜首的两个事件:
SQL*Net message from clientSQL*Net message to client| 字段 | 说明 |
|---|---|
| 事件名 | SQL*Net message from client |
| 本质 | 前台进程等待客户端发送下一条指令 |
| P1 | 客户端网络驱动类型(Thin/OCI/JDBC/OCI over TCPS …) |
| P2 | 期望接收的字节数 |
| 超时 | 无,直到客户端真的发消息 |
fetchSize = 1000。autoCommit=true,每条 DML 后都有一次往返。 ➜ 设置 useLocalTransaction=true、批量提交。SQL*Net message from client 的 平均等待时长 高,但 单次等待 低 → 批处理循环。sql_id 的等待分布,如果堆在 from client,说明 客户端代码 是瓶颈。| 字段 | 说明 |
|---|---|
| 事件名 | SQL*Net message to client |
| 本质 | 服务端已准备好数据,但客户端或网络链路“吃不下” |
| P1 | 客户端网络驱动类型 |
| P2 | 本次发送的字节数 |
| 超时 | 无 |
SDU/TDU 减少往返。LOB/LONG RAW 导致 packet loss,TCP 重传。 ➜ 网络团队抓包;数据库侧启用 SDU=65535、TDU=65535、TCP.NODELAY=YES。defaultRowPrefetch=10,结果集 100 万行时,服务端一次次“塞”数据。 ➜ 调大 defaultRowPrefetch(100~1000)或改用游标式流。AWR 报告 SQL*Net message from client 占 DB Time 60%,单次仅 0.3 ms,次数 180 M。
ASH 抽取 sql_id = 7r3m5... 对应 Java 方法 com.foo.Bar.processRow(),发现伪代码:
while (rs.next()) {
total += rs.getBigDecimal("amount");
}
在 Java 端把循环改为:
SELECT SUM(amount) INTO :1 FROM ...
一次往返搞定,事件直接消失。
BULK COLLECT + FORALLdefaultRowPrefetch、fetchSize、autoCommitping, traceroute, tcpdump, oradebug tracefile_name 抓 SDU/TDU]]>下次再看到这两个事件,别再一股脑把锅甩给网络——多数时候,真正的瓶颈在应用和数据库之间的 交互模式。
Top 5 Timed Events:
Event Waits Time(s) Avg Wait(ms) %DB Time
------------------------ ------ ------- ------------ -------
ST enqueue 12,345 18,491 1,498 31.6
这条 ST enqueue 等待直接把数据库 CPU Idle 干到个位数,业务方反馈“DDL 偶尔卡顿、批量作业跑不动”。
T enqueue 究竟是什么?
UET$(Used Extents)或 FET$(Free Extents)的操作就会申请 ST 锁,典型场景包括: • DROP / TRUNCATE / MOVE 表或分区 • ALTER TABLE … COALESCE • 大批量 INSERT/UPDATE/DELETE 触发动态扩展 • 临时段大量分配/回收(排序、hash join、索引创建)ST enqueue 占据大量 DB Time • v$session_wait 看到 p1=1414332418(enqueue 的 ID 对应 ST) • 业务会话 event="enq: ST - contention",seconds_in_wait 累积用下面一条 SQL 就能抓到“元凶”:
SELECT s.sid,
s.serial#,
s.username,
s.sql_id,
s.event,
l.type,
l.id1,
l.id2,
lo.object_name,
lo.object_type
FROM v$session s
JOIN v$lock l ON s.sid = l.sid
JOIN dba_objects lo ON l.id1 = lo.object_id
WHERE l.type = 'ST';
输出示例:
SID SERIAL# USERNAME SQL_ID EVENT TYPE OBJECT_NAME OBJECT_TYPE
---- ------- -------- ------------- --------------------- ---- ----------- -----------
123 45678 DW_BATCH 9q7x8y0g9z9z0 enq: ST - contention ST UET$ TABLE
拿到 SID 后,再去看 v$sqltext 或 DBMS_XPLAN.DISPLAY_CURSOR 就能定位到具体 SQL。 这次我们抓到的是一条 TRUNCATE PARTITION 语句,每小时跑一次,分区表字典管理 + 没开并行,导致 ST 锁长时间被占。
根因复盘
TEMPFILE 创建,而是早期 CREATE TABLESPACE … TEMPORARY 的 DMT 临时表空间。 大量排序把临时段当“公共厕所”,频繁申请/释放 ST 锁。五、根治方案:三板斧一次性解决
| 步骤 | 动作 | 备注 |
|---|---|---|
| 1 | 把所有永久表空间改为 本地管理 | EXEC DBMS_SPACE_ADMIN.TABLESPACE_MIGRATE_TO_LOCAL('USERS'); |
| 2 | 重建临时表空间为 本地管理 + TEMPFILE | CREATE TEMPORARY TABLESPACE TEMP_LMT TEMPFILE '+DATA' SIZE 20G AUTOEXTEND ON; |
| 3 | 业务侧规范 | • 大表提前 ALTER TABLE … ALLOCATE EXTENT 预分配空间 • 批量 DDL 合并窗口,避免并发 |
• ST enqueue 99% 都是 字典管理表空间 的历史包袱。 • 一条 SQL 就能定位阻塞者,但根治必须 全库 LMT + 正确临时表空间。 • 如果你还在用 DMT,建议立刻排期整改,越晚越痛苦。