PostgreSQL pending patch : pg_basebackup throttling, limit network transfer rate-白红宇

PostgreSQL 的一个限速补丁, 目前可以实现基础备份命令pg_basebackup的限速.

PostgreSQL 9.3beta2为例

安装补丁

root@db-172-16-3-33-> cd postgresql-9.3beta2root@db-172-16-3-33-> wget http://www.postgresql.org/message-id/attachment/29732/backup_throttling.patchroot@db-172-16-3-33-> patch -p1 < ./backup_throttling.patchroot@db-172-16-3-33-> gmake && gmake install

pg_basebackup

新增-r选项.

root@db-172-16-3-33-> pg_basebackup --help  -r, --max-rate         maximum transfer rate between server and client

[测试]

限速1MB/s (可以单位m, k)

pg93@db-172-16-3-39-> pg_basebackup -D $PGDATA -F p -x -P -v -h 172.16.3.33 -U postgres -r 1mWARNING:  skipping special file "./.s.PGSQL.1999"transaction log start point: 1/6F000028 on timeline 13WARNING:  skipping special file "./.s.PGSQL.1999"/pg_root/pg_subtrans/0059)207155/403043 kB (51%), 0/1 tablespace (...03/pg93/pg_root/base/16384/16385)

root@db-172-16-3-39-> sar -n DEV 5 10000|grep eth002:47:33 PM      eth0    752.00     58.00 1110626.40   7256.80      0.00      0.00      2.0002:47:38 PM      eth0    663.20     57.40 972859.20   7505.00      0.00      0.00      1.8002:47:43 PM      eth0    749.00     61.20 1107662.00   7462.00      0.00      0.00      1.6002:47:48 PM      eth0    791.80     58.40 1170254.00   7282.80      0.00      0.00      1.60

[参考]

+      
       
        
       +      
       
        +       
        
         +       The maximum amount of data transferred from server per second.+       The purpose is to limit impact of+       
         
          pg_basebackup
          on a running master server.+       
        +       
        
         +       Suffixes 
         
          k
          (kilobytes) and 
         
          m
         +       (megabytes) are accepted. For example: 
         
          10m
         +       
        +

root@db-172-16-3-33-> pg_basebackup --help  -r, --max-rate         maximum transfer rate between server and client

+/*+ * If the progress is more than what max_rate allows, sleep.+ *+ * Do not call if max_rate == 0.+ */+static void+enforce_max_rate()+{+       int64           min_elapsed,+                               now,+                               elapsed,+                               to_sleep;++       int64           last_chunk;++       last_chunk = totaldone - last_measured;++       /* The measurements shouldn't be more frequent then necessary. */+       if (last_chunk < RATE_MIN_SAMPLE)+               return;+++       now = localGetCurrentTimestamp();+       elapsed = now - last_measured_time;++       /*+        * max_rate relates to seconds, thus the expression in brackets is+        * milliseconds per byte.+        */+       min_elapsed = last_chunk * (USECS_PER_SEC / max_rate);++       /*+        * min_elapsed is the minimum time we must have spent to get here. If we+        * spent less, let's wait.+        */+       to_sleep = min_elapsed - elapsed;+       if (to_sleep > 0)+               pg_usleep((long) to_sleep);++       last_measured = totaldone;+       last_measured_time = now + to_sleep;+}+ /*  * Write a piece of tar data@@ -852,6 +977,8 @@ ReceiveTarFile(PGconn *conn, PGresult *res, int rownum)                totaldone += r;                if (showprogress)                        progress_report(rownum, filename);+               if (max_rate > 0)+                       enforce_max_rate();        }