oracle - 解决 ORA-4031 “无法分配 x 字节的共享内存”

Question

我需要一些有关如何诊断和解决此问题的指示。我不知道这是一个简单的服务器设置问题还是应用程序设计问题（或两者兼而有之）。

这个 Oracle XE 数据库每隔几个月就会报告一次或两次 ORA-4031 错误。它并没有始终如一地指向 sga 的任何特定部分。最近的一个例子是：

ORA-04031: unable to allocate 8208 bytes of shared memory ("large pool","unknown object","sort subheap","sort key")

当这个错误出现时，如果用户不断刷新，点击不同的链接，他们通常会在不同的时间收到更多的此类错误，然后很快就会出现“404 not found”页面错误。

重新启动数据库通常会在一段时间内解决问题，然后一个月左右再次出现，但很少出现在程序中的同一位置（即它似乎没有链接到任何特定的代码部分）（上面的例子Apex 页面从表格中对 5000 多行进行排序时引发错误）。

我尝试sga_max_size从 140M 增加到 256M，希望这会有所帮助。当然，我不知道这是否有帮助，因为我不得不重新启动数据库来更改设置:)

我在具有 512MB RAM 的 Oracle Enterprise Linux 5 机器上运行 Oracle XE 10.2.0.1.0。该服务器仅运行数据库、Oracle Apex (v3.1.2) 和 Apache Web 服务器。我使用几乎所有默认参数安装它，并且它已经运行了一年左右。大多数问题我都可以通过调整应用程序代码自行解决；它没有被大量使用，也不是关键业务系统。

这些是我认为可能相关的一些当前设置：

pga_aggregate_target        41,943,040
sga_max_size              268,435,456
sga_target                146,800,640
shared_pool_reserved_size   5,452,595
shared_pool_size          104,857,600

如果有任何帮助，这里是当前的 SGA 大小：

Total System Global Area  268435456 bytes
Fixed Size                  1258392 bytes
Variable Size             251661416 bytes
Database Buffers           12582912 bytes
Redo Buffers                2932736 bytes

score 7 · Accepted Answer

即使您使用的是 ASMM，您也可以为大型池设置最小大小（MMAN 不会将其缩小到该值以下）。您也可以尝试固定一些对象并增加 SGA_TARGET。

score 5 · Accepted Answer

Don't forget about fragmentation. If you have a lot of traffic, your pools can be fragmented and even if you have several MB free, there could be no block larger than 4KB. Check size of largest free block with a query like:

 select
  '0 (<140)' BUCKET, KSMCHCLS, KSMCHIDX,
  10*trunc(KSMCHSIZ/10) "From",
  count(*) "Count" ,
  max(KSMCHSIZ) "Biggest",
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
from
  x$ksmsp
where
  KSMCHSIZ<140
and
  KSMCHCLS='free'
group by
  KSMCHCLS, KSMCHIDX, 10*trunc(KSMCHSIZ/10)
UNION ALL
select
  '1 (140-267)' BUCKET,
  KSMCHCLS,
  KSMCHIDX,
  20*trunc(KSMCHSIZ/20) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
from
  x$ksmsp
where
  KSMCHSIZ between 140 and 267
and
  KSMCHCLS='free'
group by
  KSMCHCLS, KSMCHIDX, 20*trunc(KSMCHSIZ/20)
UNION ALL
select
  '2 (268-523)' BUCKET,
  KSMCHCLS,
  KSMCHIDX,
  50*trunc(KSMCHSIZ/50) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
from
  x$ksmsp
where
  KSMCHSIZ between 268 and 523
and
  KSMCHCLS='free'
group by
  KSMCHCLS, KSMCHIDX, 50*trunc(KSMCHSIZ/50)
UNION ALL
select
  '3-5 (524-4107)' BUCKET,
  KSMCHCLS,
  KSMCHIDX,
  500*trunc(KSMCHSIZ/500) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
from
  x$ksmsp
where
  KSMCHSIZ between 524 and 4107
and
  KSMCHCLS='free'
group by
  KSMCHCLS, KSMCHIDX, 500*trunc(KSMCHSIZ/500)
UNION ALL
select
  '6+ (4108+)' BUCKET,
  KSMCHCLS,
  KSMCHIDX,
  1000*trunc(KSMCHSIZ/1000) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
from
  x$ksmsp
where
  KSMCHSIZ >= 4108
and
  KSMCHCLS='free'
group by
  KSMCHCLS, KSMCHIDX, 1000*trunc(KSMCHSIZ/1000);

Code from

score 2 · Accepted Answer

All of the current answers are addressing the symptom (shared memory pool exhaustion), and not the problem, which is likely not using bind variables in your sql \ JDBC queries, even when it does not seem necessary to do so. Passing queries without bind variables causes Oracle to "hard parse" the query each time, determining its plan of execution, etc.

https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::p11_question_id:528893984337

Some snippets from the above link:

"Java supports bind variables, your developers must start using prepared statements and bind inputs into it. If you want your system to ultimately scale beyond say about 3 or 4 users -- you will do this right now (fix the code). It is not something to think about, it is something you MUST do. A side effect of this - your shared pool problems will pretty much disappear. That is the root cause. "

"The way the Oracle shared pool (a very important shared memory data structure) operates is predicated on developers using bind variables."

" Bind variables are SO MASSIVELY important -- I cannot in any way shape or form OVERSTATE their importance. "

score 0 · Accepted Answer

The following are not needed as they they not fix the error:

ps -ef|grep oracle
Find the smon and kill the pid for it
SQL> startup mount
SQL> create pfile from spfile;

Restarting the database will flush your pool and that solves a effect not the problem.

Fixate your large_pool so it can not go lower then a certain point or add memory and set a higher max memory.

score -1 · Accepted Answer

This is Oracle bug, memory leak in shared_pool, most likely db managing lots of partitions. Solution: In my opinion patch not exists, check with oracle support. You can try with subpools or en(de)able AMM ...

score -2 · Accepted Answer

Error

ORA-04031: unable to allocate 4064 bytes of shared memory ("shared pool","select increment$,minvalue,m...","sga heap(3,0)","kglsim heap")

Solution: by nepasoft nepal

1.-
```
ps -ef|grep oracle
```
2.- Find the smon and kill the pid for it

3.-

SQL> startup mount
ORACLE instance started.

Total System Global Area 4831838208 bytes
Fixed Size                  2027320 bytes
Variable Size            4764729544 bytes
Database Buffers           50331648 bytes
Redo Buffers               14749696 bytes
Database mounted.

4.-

SQL> alter system set shared_pool_size=100M scope=spfile;

System altered.

5.-

SQL> shutdown immediate

ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.

6.-

SQL> startup
ORACLE instance started.

Total System Global Area 4831838208 bytes
Fixed Size                  2027320 bytes
Variable Size            4764729544 bytes
Database Buffers           50331648 bytes
Redo Buffers               14749696 bytes
Database mounted.
Database opened.

7.-

SQL> create pfile from spfile;

File created.

SOLVED

oracle - 解决 ORA-4031 “无法分配 x 字节的共享内存”

6 回答 6

Error

Solution: by nepasoft nepal

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