在 GaussDB 启动的过程中，可以从日志中清晰的看到，后台依次启动了一系列的线程。
GaussDB 100采用单进程、多线程结构。服务器在运行时由各种内存数据结构和一系列线程组成，不同类型的线程完成不同的任务，这其中包括 LGWR / DBWR / CKPT / SMON / STATS ，基本上与 Oracle 命名保持一致。
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|77309420628|INFO>[LOG] file '/ssd_data/gaussdb/gaussdata/log/enmotech_alarm.log' is added [srv_param.c:488]
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[LOG] file '/ssd_data/gaussdb/gaussdata/log/run/zengine.rlog' is added [cm_log.c:643]
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] LSNR_ADDR = 127.0.0.1
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] LSNR_PORT = 1611
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] DATA_BUFFER_SIZE = 2G
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] SHARED_POOL_SIZE = 1G
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] LOG_BUFFER_SIZE = 64M
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] LOG_BUFFER_COUNT = 8
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] TEMP_BUFFER_SIZE = 1G
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] SESSIONS = 1500
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] CONTROL_FILES = (/gaussdb/gaussdata/data/cntl1, /gaussdb/gaussdata/data/cntl2, /gaussdb/gaussdata/data/cntl3)
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] DBWR_PROCESSES = 8
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] INSTANCE_NAME = enmotech
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|9300|INFO>[PARAM] ENABLE_SYSDBA_LOGIN = TRUE
UTC+8 2019-12-06 17:05:28.691|ZENGINE|00000|206158439508|INFO>starting instance(normal)
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9302|INFO>lgwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9303|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9305|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9306|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9304|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9307|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9308|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9309|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9310|INFO>dbwr thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9311|INFO>ckpt thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9312|INFO>smon thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9313|INFO>stats thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9314|INFO>index page recycle thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9315|INFO>rollback thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9316|INFO>rollback thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9317|INFO>rmon thread started
UTC+8 2019-12-06 17:05:28.743|ZENGINE|00000|9318|INFO>job master thread started
UTC+8 2019-12-06 17:05:28.782|ZENGINE|00000|9319|INFO>reactor thread started
UTC+8 2019-12-06 17:05:28.782|ZENGINE|00000|9300|INFO>local ip: 127.0.0.1
UTC+8 2019-12-06 17:05:28.782|ZENGINE|00000|9320|INFO>tcp-lsnr thread started
UTC+8 2019-12-06 17:05:28.782|ZENGINE|00000|9321|INFO>uds-lsnr thread started
UTC+8 2019-12-06 17:05:28.788|ZENGINE|00000|9300|INFO>SSL disabled: server certificate or private key file is not available.
UTC+8 2019-12-06 17:05:28.788|ZENGINE|00000|9300|INFO>start to alter database MOUNT
UTC+8 2019-12-06 17:05:28.823|ZENGINE|00000|9300|INFO>[ARCH] Init arch is_archive 0
UTC+8 2019-12-06 17:05:28.823|ZENGINE|00000|9300|INFO>[ARCH] Initialization complete
UTC+8 2019-12-06 17:05:28.823|ZENGINE|00000|9300|INFO>sucessfully alter database MOUNT
UTC+8 2019-12-06 17:05:28.823|ZENGINE|00000|206158439508|INFO>start to alter database OPEN
UTC+8 2019-12-06 17:05:28.841|ZENGINE|00000|140733193397332|INFO>[ARCH] Start ARCH thread for ARCHIVE_DEST_1[/ssd_data/gaussdb/gaussdata/archive_log]
UTC+8 2019-12-06 17:05:28.841|ZENGINE|00000|6477904490279216212|INFO>The last shutdown is a consistent shutdown
UTC+8 2019-12-06 17:05:28.841|ZENGINE|00000|9300|INFO>database start recovery
UTC+8 2019-12-06 17:05:28.841|ZENGINE|00000|9300|INFO>recovery from file:1,point:83006,lfn:15709
UTC+8 2019-12-06 17:05:28.841|ZENGINE|00000|9300|INFO>recovery expected least end with file:1,point:83006,lfn:15709
UTC+8 2019-12-06 17:05:28.860|ZENGINE|00000|140733193397332|INFO>[RCY] recovery real end with file:1,point:83006,lfn:15709
UTC+8 2019-12-06 17:05:28.860|ZENGINE|00000|140733193397332|INFO>[RCY] current lfn 15709, rcy point lfn 15709, consistent point 15709, lrp point lfn 15709
UTC+8 2019-12-06 17:05:28.889|ZENGINE|00000|140642999084116|INFO>no valid standby configuration
UTC+8 2019-12-06 17:05:28.889|ZENGINE|00000|9300|INFO>[DB] sse42 available 1
UTC+8 2019-12-06 17:05:28.889|ZENGINE|00000|9300|INFO>sucessfully alter database OPEN
UTC+8 2019-12-06 17:05:28.889|ZENGINE|00000|9300|INFO>instance started
UTC+8 2019-12-06 17:05:28.942|ZENGINE|00000|9315|INFO>rollback thread closed [knl_tran.c:1306]
UTC+8 2019-12-06 17:05:28.942|ZENGINE|00000|9316|INFO>rollback thread closed [knl_tran.c:1306]
UTC+8 2019-12-06 17:05:29.751|ZENGINE|00053|9327|INFO>load table parts: load table parts, uid: 0, tid: 289, partcnt: 3962 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.751|ZENGINE|00053|13850784198304879|INFO>load index parts: load index parts, uid: 0, tid: 289, iid: 0, index partcnt: 3962 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.768|ZENGINE|00053|9327|INFO>load table parts: load table parts, uid: 0, tid: 275, partcnt: 35 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.782|ZENGINE|00053|9327|INFO>load table parts: load table parts, uid: 0, tid: 285, partcnt: 35 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.787|ZENGINE|00053|14135557709898863|INFO>load index parts: load index parts, uid: 0, tid: 285, iid: 0, index partcnt: 35 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.791|ZENGINE|00054|9328|INFO>load table parts: load table parts, uid: 0, tid: 266, partcnt: 3962 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.791|ZENGINE|00054|13855182244815984|INFO>load index parts: load index parts, uid: 0, tid: 266, iid: 0, index partcnt: 3962 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.791|ZENGINE|00054|9328|INFO>load table parts: load table parts, uid: 0, tid: 263, partcnt: 3962 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.791|ZENGINE|00054|9328|INFO>load table parts: load table parts, uid: 0, tid: 264, partcnt: 3962 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.791|ZENGINE|00054|13855182244815984|INFO>load index parts: load index parts, uid: 0, tid: 264, iid: 0, index partcnt: 3962 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.793|ZENGINE|00054|9328|INFO>load table parts: load table parts, uid: 0, tid: 265, partcnt: 3962 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.793|ZENGINE|00054|14418132198237296|INFO>load index parts: load index parts, uid: 0, tid: 265, iid: 0, index partcnt: 3962 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.795|ZENGINE|00053|140642999084143|INFO>load table parts: load table parts, uid: 0, tid: 287, partcnt: 35 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.799|ZENGINE|00053|9327|INFO>load table parts: load table parts, uid: 0, tid: 291, partcnt: 1 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.799|ZENGINE|00053|16106982058501231|INFO>load index parts: load index parts, uid: 0, tid: 291, iid: 0, index partcnt: 1 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.801|ZENGINE|00053|46913927783535|INFO>load table parts: load table parts, uid: 0, tid: 290, partcnt: 1 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.801|ZENGINE|00053|13845290935133295|INFO>load index parts: load index parts, uid: 0, tid: 290, iid: 0, index partcnt: 1 [knl_partition.c:2358]
UTC+8 2019-12-06 17:05:29.805|ZENGINE|00053|9327|INFO>load table parts: load table parts, uid: 0, tid: 293, partcnt: 35 [knl_partition.c:1493]
UTC+8 2019-12-06 17:05:29.811|ZENGINE|00053|14971190841975919|INFO>load index parts: load index parts, uid: 0, tid: 293, iid: 0, index partcnt: 35 [knl_partition.c:2358]
操作系统的进程则仅有核心一个：
[root@enmodb3 run]# ps -ef|grep eygle
root 5453 5400 0 10:30 pts/0 00:00:00 su - eygle
eygle 5454 5453 0 10:30 pts/0 00:00:00 -bash
eygle 9300 1 0 17:05 pts/0 00:00:08 /ssd_data/gaussdb/1.0.0/bin/zengine open -D /ssd_data/gaussdb/gaussdata
官方文档说明如下：
GaussDB 100为保证SYS用户在紧急情况下可以操作数据库，为SYS用户预留5个独立会话、1个工作线程。
日常运行中有16个默认的自治事务会话（可以通过AUTONOMOUS_SESSIONS、KNL_AUTONOMOUS_SESSIONS参数设置），32个预留的内部使用会话，用于资源回收、checkpoint等，16个sql并行框架会话。内部使用会话功能如下表所示。
SID | session功能 |
|---|---|
0 | 切换实例状态，例如kernel启停，主机降备，备机升主等 |
1 | lgwr线程 |
2 | ckpt线程 |
3 | smon线程 |
4 | 预留，暂未使用 |
5 | undo preload线程 |
6 | arch线程 |
7 | rst线程 |
8 | lsnr线程 |
9 | mrp线程 |
10 | 预留，暂未使用 |
11 | fal线程 |
12 | timer线程 |
13 | rollback线程 |
14 | 预留，暂未使用 |
15 | log async线程 |
16 | gts synchronizer线程 |
17 | rcy线程 |
18 | 预留，暂未使用 |
19 | 预留，暂未使用 |
20 | 预留，暂未使用 |
21 | 预留，暂未使用 |
22 | 预留，暂未使用 |
23 | 预留，暂未使用 |
24 | 预留，暂未使用 |
25 | shd trans clean线程 |
26 | stats线程 |
27 | 插入统计信息到临时表，加载临时表的统计信息到dc上 |
28 | 加载分布式的节点 |
29 | job线程 |
30 | index page recycle线程 |
31 | 预留，暂未使用 |
这是非常早期的信息，会随着版本变化而变化。
