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java.sql.BatchUpdateException: IO Error: Connection reset

InPractice — Mon, 20 Feb 2017 01:28:00 GMT

during analysis of "IO Error: Connection reset", many articles mentioned that it could be caused by java security code (accessing /dev/random) used in JDBC connection. However it is not the root cause in my case. In my environment, Java already use /dev/urandom. 1. $JAVA_HOME/jre/lib/security/java.security securerandom.source=file:/dev/./urandom 2. check with strace. only -Djava.security.egd=file:/dev/../dev/urandom will trigger system call (read on /dev/urandom) all other other path format like below are OK. -Djava.security.egd=file:/dev/./urandom -Djava.security.egd=file:///dev/urandom 3. Keep checking the retropy size, I have never seen it is exhaused. while [ 1 ]; do cat /proc/sys/kernel/random/entropy_avail sleep 1 done usually the avail is in the range from 1000 to 3000. so far, there is no clue about the root cause of "IO Error: Connection reset".

InPractice 2017-02-20 09:28 发表评论

Lessons learned - Oracle GI and Database Installation on SUSE 12

InPractice — Thu, 28 Jul 2016 08:55:00 GMT

I encountered many issue during installation of Oracle Grid Infrastructure(GI) and Database; with the help of ariticle and documents found through Google search engine, I finally made it. for records, here is the details issues encountered and solutions applied. Major issues were encountered during GI installation. Pre-installation tasks. Issue 1: swapspace is not big enough; (1.3.1 Verify System Requirements) grep MemTotal /proc/meminfo 264G grep SwapTotal /proc/meminfo 2G during OS installation, I take default option and swap space is only 2G. Oracle recommend to have more than 16G swap space in case of more that 32G RAM. dd if=/dev/zero of=/home/swapfile bs=1024 count=33554432 33554432+0 records in 33554432+0 records out 34359738368 bytes (34 GB) copied mkswap /home/swapfile mkswap /home/swapfile chmod 0600 /home/swapfile lessons learned: setup swap space properly according to DB requirement when installing OS. Issue 2: cannot find oracleasm-kmp-default from Oracle site. (1.3.6 Prepare Storage for Oracle Automatic Storage Management) install oracleasmlib and oracleasm-support is easy, just download them from Oracle and install them; Originally oracleasm kernel is provided by Oracle, but now I cannot find it from Oracle; finally I realized that oracleasm kernel is now provided by OS vendor; In my case, it should be installed from SUSE disk; a. to get its name oracleasm-kmp-default zypper se oracle b. map dvd and install zypper in oracleasm-kmp-default rpm -qa|grep oracleasm oracleasm-kmp-default-2.0.8_k3.12.49_11-3.20.x86_64 oracleasm-support-2.1.8-1.SLE12.x86_64 oracleasmlib-2.0.12-1.SLE12.x86_64 asm configure -i asm createdisk DATA /dev/<...> asm listdisks --DATA ls /dev/oracleasm/disks Installation tasks: Issue 3: always failed due to user equivalence check after starting installer OUI with user oracle. however if I manully check with runcluvfy, no issue found at all. ./runcluvfy.sh stage -pre crsinst -n , -verbose I worked around it by using another user to replace user oracle. but it triggered next issue. Issue 4: cannot see ASM disks in OUI. no matter how I change the disk dicovery path. the disk list is empty. but I can find disk manully. /usr/sbin/oracleasm-discover 'ORCL:*' Discovered disk: ORCL:DATA Root cause is that the ASM is configured and created with user oracle. and I aming installing GI with different user other than oracle; so I cannot see the Disk created. change owner of disk device file solved the issue. ls /dev/oracleasm/disks chown /dev/oracleasm/disks -R Issue 5: root.sh execution failed. Failed to create keys in the OLR, rc = 127, Message: clscfg.bin: error while loading shared libraries: libcap.so.1: cannot open shared object file: No such file or directory fixed the issue with command below: zypper in libcap1 ohasd failed to start Failed to start the Clusterware. Last 20 lines of the alert log follow: 2016-07-24 23:10:28.502: [client(1119)]CRS-2101:The OLR was formatted using version 3. I found a good document from SUSE, Oracle RAC 11.2.0.4.0 on SUSE Linux Enterprise Server 12 - x86_64, it make it clear that SUSE 12 is supported by Oracle GI 11.2.0.4, it also mentioned Patch 18370031. "During the Oracle Grid Infrastructure installation, you must apply patch 18370031 before configuring the software that is installed. " The patch 18370031 is actually mentioned in "Oracle quick installation guide on Linux", but not mentioned in "Oracle quick installation guide on Linux". I majored followed up with later one and missed Patch 18370031. issue disappeared after I installed the patch 18370031. ./OPatch/opatch napply -oh -local /18370031 Errors in file : ORA-27091: unable to queue I/O ORA-15081: failed to submit an I/O operation to a disk ORA-06512: at line 4 solved by change owner of disk DATA related file ls -l /dev/oracleasm/iid chown on folder /dev/oracleasm/iid and some .* hidden file. Issue during DB installation Issue 6: report error: in invoking target 'agent nmhs' vi $ORACLE_HOME/sysman/lib/ins_emagent.mk Search for the line $(MK_EMAGENT_NMECTL) Change it to: $(MK_EMAGENT_NMECTL) -lnnz11 refer to https://community.oracle.com/thread/1093616?tstart=0

InPractice 2016-07-28 16:55 发表评论

卸蝲Ubuntu需要注意的地方

InPractice — Mon, 11 Apr 2011 10:19:00 GMT

很多�q�前装了(ji��n)Ubuntu�?/span>Windows的双�pȝ��Q�最�q�因为有�?ji��n)专门的电(sh��)脑来�?/span>Ubuntu�Q�所以把原先�?sh��)脑上�?/span>Ubuntu卸蝲�?ji��n)，�l�果�pȝ��不能引导�?ji��n)。因�?/span>GRUB的原理是控制权从MBR�?/span>Ubuntu�pȝ��盘，然后Ubuntu�pȝ��盘再提供�?/span>windows的引对{��现�?/span>Ubuntu�pȝ��被卸载了(ji��n)。这个启动的链条也就断了(ji��n)�?br />
�q�个问题本��n不难解决�Q�借了(ji��n)一�?/span>Windows安装盘，恢复一�?/span>MBR卛_��。但是这个需�?/span>windows�pȝ��?/span>Administrator密码。而我的系�l�不是我装的�Q�我�Ҏ(gu��)��不知道这个密码�?br />
有的帖子提到破解Administrator密码�Q�试�?ji��n)一下，觉得太麻�?ch��)�?ji��n)。因为电(sh��)脑上有数据，也不能重装�?/span>

最后的解决�Ҏ(gu��)��是在原先�?/span>Ubuntu分区上安装一个新�?/span>Windows。这样变成了(ji��n)windows的双�pȝ��。安装完重启之后可以�q�入��M��一个系�l�（新的或者旧�?/span>Windows�Q�。安装的�q�程�?/span>MBR被自动更��C��(ji��n)。再下来��改一下老系�l�的Administrator密码�Q�删除掉多于�?/span>Windows新系�l�即可�?/span>

InPractice 2011-04-11 18:19 发表评论

InPractice — Fri, 11 Feb 2011 03:02:00 GMT

用Gmail的时候不��心(j��)点了(ji��n)"存档"按钮�Q�一��重要的邮�g��此消失�?ji��n)好几天�Q�今天才机缘巧合扑ֈ��?br />
在网�l�上查到的解释是�Q?br /> 存档�?x��)将邮�g从收件箱�U�至所有邮�Ӟ��q�样�(zh��n)�不必删除邮件就可以整理收�g��?br />
难以理解�Q�坦率地��_(d��)��q�个功能�Ҏ(gu��)��来说是徒增烦(ch��)恹{��看来�Q何工具都需要你去适应�Q�磨合�?

InPractice 2011-02-11 11:02 发表评论

华容道游戏的解决

InPractice — Mon, 16 Aug 2010 05:49:00 GMT

最�q�买�?ji��n)一个叫�?#8220;华容�?#8221;的玩��L(f��ng)��儿子晚。这个游戏虽然号�U�是中国四大古典智力游戏之一。其实不�q�百�q�历�Ԍ��而且是从国外引进的。不�q�本地化做得非常好，也算是创造性地吸收国外文明�?br />
手工解决�q�个游戏有点隑ֺ��Q�当然已�l�有人给��Z��(ji��n)解法�Q�不�q�我�q�是自己用编�E�的方式解决�?ji��n)一遍。发现自己在�q�方面的�~�程�q�是比较弱。大部分旉��花在�?ji��n)调试上�?br />
刚开始是用的深度优先搜烦(ch��)。大致知道了(ji��n)�{�案应该长什么样。后来改�q��ؓ(f��)�q�度优先搜烦(ch��)�Q�得��C��(ji��n)最优的解法。还有一个就是原先只考虑每次最多移动一根{��后来发��C��l�的定义是一个块的所有连�l�移动都��作一步。相应地修改�?ji��n)实现算法�?br />
最隄��是做界面。�ؓ(f��)�?ji��n)调试，随便写�?ji��n)个Applet。但是给我儿子玩�Q�就觉得拿不出手�?ji��n)�?br />

InPractice 2010-08-16 13:49 发表评论

Meta Information

InPractice — Fri, 04 Jun 2010 22:44:00 GMT

Just use this blog to share some meta information.

git://github.com/ueddieu/mmix.git

http://github.com/ueddieu/mmix.git

InPractice 2010-06-05 06:44 发表评论

Notes on Gentoo Installation

InPractice — Thu, 03 Jun 2010 08:33:00 GMT

After two weeks' struggle, I have successfully installed Gentoo, a popular GNU/Linux Distribution. For Records, the obstacles I encountered are listed below. (but I can not remember the solution exactly)

0. failed to emerge gpm when I install the links package. If I recall correctly, it is resolved by install gpm manually

1. I encounter issue when I install glib 2.22.5. no update-desktop-database. which is in dev-util/desktop-file-utils. When I try to emerge it, there is a circular dependency on glib. no solution and I forget How I resolve the problem.

2. later after I install glib, with ~amd64 keyword I can install gpm-1.20.6, but it conflicts with the manually inatalled gpm. I remove the conflicted file and emerge successfully.

3. Failed to emerge tiff. edit packages.keywords to add the following. / ~amd64 I am able to use latest tiff in beta-version, which is unstable and masked out.

4. later atk-1.28.0 failed to emerge. edit /etc/make.conf with the following. FEATURES="-stricter". then emerge successfully with only some complain. with out this seting. the warining from GCC will cause that emerge fail.

5. when I run emerge --update system actually gcc will be upgraded from 4.3.4 to 4.4.3. but it failed because of compilation warning, again. add "-stricter" into Features variable in /etc/make.conf work around it.

6. The installation takes a long time, the KDE itself take more than 10 hours. There is still a lot of improvement space! Anyway, it is nice to be able to use it daily.

InPractice 2010-06-03 16:33 发表评论

为SVN客户端设�|�Proxy

InPractice — Wed, 21 Apr 2010 09:00:00 GMT

在C:\Documents and Settings\\Application Data\Subversion\servers文�g中加�?br /> all=*.*

[all]
http-proxy-host = ***.**.com
http-proxy-port = 8080

�q�里的all映射到所有的Server�?br />
�|�络环境的复杂给我们的工作带来了(ji��n)一些媄(ji��ng)响。就拿Proxy的设�|�来��_(d��)��本来理想的情冉|��在全局做一个设�|�就可以�?ji��n)，但是事实上我们要为每个程序做讄��Q�而且语法�q�不一栗��?br />

InPractice 2010-04-21 17:00 发表评论

InPractice — Tue, 13 Apr 2010 08:13:00 GMT

今天从word文档中拷贝脚本到命��o(h��)行执行。没有想到的是Word自动加入�?ji��n)空��|��D��执行��p�|。具体如下�?br /> call ttGridCreate('$TT_GRID');
被word变成�?br /> call ttGridCreate(' $TT_GRID');
�q�个�I�格可不�Ҏ(gu��)��被发玎ͼ��其你不是脚本作者的时候。提高警惕！

InPractice 2010-04-13 16:13 发表评论

InPractice — Fri, 09 Apr 2010 07:57:00 GMT

今天做了(ji��n)一个简单的性能��试。比较访问Java对象属性的各种�Ҏ(gu��)��的性能差异�?br /> 1. 直接讉K��对象的属性�?br /> 2. 用方法访问对象的属性�?br /> 3. 用Map来存储和讉K��?br /> 4. 反射�Q�Field 讉K��?br /> 5. 反射�Q�Method讉K��?br />
重复100�ơ，�l�果如下(单位为纳�U�）(j��)�?br /> * 100 field access, 14,806

* 100 method access, 20,393

* 100 map access, 66,489

* 100 reflection field access, 620,190

* 100 reflection method access, 1,832,356

重复100000�ơ，�l�果如下(单位为纳�U�）(j��)�?br /> *100000 field access, 2,938,362
*100000 method access, 3,039,772
*100000 map access, 10,784,052
*100000 reflection field access, 144,489,034
*100000 reflection method access, 37,525,719

��q��果可见：(x��)
1。getter/setter 的性能已经接近直接属性访问（大约�?0�Q�）(j��)�Q�没有必要担�?j��)getter/setter的性能而采用直接属性访问�?br /> 2。用Map代替POJO的代价大�U�是比getter/setter慢三倍�?br /> 3。反��访问比getter/setter�?0�?50倍。慎用。追求动态性的时候也要注意不菲的性能代�h(hu��n)�?br /> 4。注意重复次数增加到100000�ơ，�Ҏ(gu��)��讉K��和属性访问的差距�~�小�Q�更有意思的是，反射的Method讉K��比Field讉K��快四倍。这主要是JIT的作用�?br />
该测试结果和原先的猜惛_��本符合。但是性能评估很容易得到片面的�l�论�Q�如果有错误的地方，请大家不吝指正。谢谢�?br />

InPractice 2010-04-09 15:57 发表评论