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
pg_basebackup 新增-r选项.
[测试]
root@db-172-16-3-33-> cd postgresql-9.3beta2
root@db-172-16-3-33-> wget http://www.postgresql.org/message-id/attachment/29732/backup_throttling.patch
root@db-172-16-3-33-> patch -p1 < ./backup_throttling.patch
root@db-172-16-3-33-> gmake && gmake installpg_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)
[参考]
pg93@db-172-16-3-39-> pg_basebackup -D $PGDATA -F p -x -P -v -h 172.16.3.33 -U postgres -r 1m
WARNING: skipping special file "./.s.PGSQL.1999"
transaction log start point: 1/6F000028 on timeline 13
WARNING: 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 eth0
02:47:33 PM eth0 752.00 58.00 1110626.40 7256.80 0.00 0.00 2.00
02:47:38 PM eth0 663.20 57.40 972859.20 7505.00 0.00 0.00 1.80
02:47:43 PM eth0 749.00 61.20 1107662.00 7462.00 0.00 0.00 1.60
02:47:48 PM eth0 791.80 58.40 1170254.00 7282.80 0.00 0.00 1.60[参考]
2.
3.
4.
+ <term><option>--max-rate</option></term>
+ <listitem>
+ <para>
+ The maximum amount of data transferred from server per second.
+ The purpose is to limit impact of
+ <application>pg_basebackup</application> on a running master server.
+ </para>
+ <para>
+ Suffixes <literal>k</literal> (kilobytes) and <literal>m</literal>
+ (megabytes) are accepted. For example: <literal>10m</literal>
+ </para>
+ </listitem>3.
root@db-172-16-3-33-> pg_basebackup --help
-r, --max-rate maximum transfer rate between server and client4.
+/*
+ * 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();
} 