ORACLE进程的内存结构解析
<DIV><P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center" align=center><SPAN lang=EN-US><FONT face="Times New Roman">ORACLE</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进程的内存结构解析</SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"> </FONT></SPAN></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">每个</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ORACLE</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进程从上低地址到高地址</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">分别由进程序的执行体</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,PGA SESSION HEAP,,SGA,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">共享库</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">空闲空间和</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">STACK</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">区组成</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">32</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位上的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">LINUX</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">上的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一般都是由</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">08048000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">处开始加载</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ORACLE</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序的执行体</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">0X20000000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">处开始加载</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">FIXSGA,REDO BUFFER</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作系统的特殊区域直到</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">0X20800000,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一般大小为</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">8M</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">左右</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.REDO BUFFER</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">0X20147000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">开始加载</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">那么</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">FIXSGA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">大小就可以通过</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">0X20147000-0X20000000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">算出来</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">共享内存再以粒度的方式被分割</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN lang=EN-US><FONT face="Times New Roman">Variable Size</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">就从</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">20800000</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">处开始载</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">根据具体的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ORACLE</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">配置</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可能大小不一样</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以通过</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ORADEBUG IPC</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来查看具体的共享内存情况</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">OS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">级别上可以通过</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">PMAP <</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进程</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">ID></FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来查看某个进程的内存分布</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以通过</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">SQLPLUS</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">SHOW SGA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">或者是查看</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">V$SGA</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">X$KSMSD</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来得到各个区域的大小信息</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">从</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">10.1g</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">开始引入</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">X$KSMGE,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以反映当前的内存的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">GRANULE</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">分配情况</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">通过以下查询</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">SQL> select grantype,granstate,count(gransize)</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>2<SPAN style="mso-spacerun: yes"> </SPAN>from x$ksmge</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>3<SPAN style="mso-spacerun: yes"> </SPAN>where granstate<>'INVALID'</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes"> </SPAN>4<SPAN style="mso-spacerun: yes"> </SPAN>group by grantype,granstate;</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN lang=EN-US><FONT face="Times New Roman">7</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">BUFFER POOL;1,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">SHARD POOL</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在某些情况内存可能并没有被用完</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">(PRE_PAGE_SGA),</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">比如我们分本配了</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">32G,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">实际只使用了</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">20G</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">就可以满足需求了</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">通过这个查询就可以找出当前合适的内存大小</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">以防止不必要的浪费</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">.</FONT></SPAN></P></DIV>
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