ORA-01555 encountered with huge elapsed time discrepancies in alert and awr

We encountered the well-known ORA-1555 error recently : Fri Jun 23 21:07:02 2017 ORA-01555 caused by SQL statement below (SQL ID: a520vskru5tmy, Query Duration=3304 sec, SCN: 0x010a.b517cc1a): SELECT BOND_REPO_DEAL_F.BOND_REPO_DEAL_ID … Query Duration is 3304 seconds, wow! But when I checked the AWR report, it states the Elapsed time for the SQL is only 19.29 seconds.… Continue reading ORA-01555 encountered with huge elapsed time discrepancies in alert and awr

Segmentation Fault

https://kb.iu.edu/d/aqsj What are segmentation faults (segfaults), and how can I identify what’s causing them? http://www.cprogramming.com/debugging/segfaults.html Debugging Segmentation Faults and Pointer Problems https://sourceware.org/gdb/current/onlinedocs/gdb/ Debugging with GDB http://visualgdb.com/gdbreference/commands/ GDB Command Reference (gdb) info frame Stack level 0, frame at 0xb75f7390: eip = 0x804877f in base::func() (testing.cpp:16); saved eip 0x804869a called by frame at 0xb75f73b0 source language c++.… Continue reading Segmentation Fault

Tcp Zero Window

https://www.wireshark.org/docs/wsug_html_chunked/ChAdvReassemblySection.htmlhttps://blog.apnic.net/2014/12/15/ip-mtu-and-tcp-mss-missmatch-an-evil-for-network-performance/https://wiki.wireshark.org/TCP%20ZeroWindow http://wesmorgan.blogspot.jp/2011/03/tcp-zero-windows-and-why-they-can-be.html TCP Zero Windows – and Why They Can Be VERY Bad TCP zero windows FIN says “i finished talking to you, but i’ll still listen to everything you have to say until you’re done” RST says “there is no conversation. i won’t say anything and i won’t listen to anything you say” –… Continue reading Tcp Zero Window

Breaking yum infinite loop

When executing “yum update openssl*”, it seems yum runs into infinite loop: –> Running transaction check —> Package gmp.x86_64 0:4.3.1-7.el6_2.2 will be updated –> Processing Dependency: libgmp.so.3()(64bit) for package: cloog-ppl-0.15.7-1.2.el6.x86_64 –> Processing Dependency: libgmp.so.3()(64bit) for package: ppl-0.10.2-11.el6.x86_64 —> Package python.x86_64 0:2.6.6-29.el6_2.2 will be updated –> Processing Dependency: python(abi) = 2.6 for package: pygtksourceview-2.8.0-1.el6.x86_64 –> Processing… Continue reading Breaking yum infinite loop