ORA-07445: exception encountered: core dump [nstimexp()+45] [SIGSEGV] [ADDR:0x58] [PC:0x7F42ABB] [Address not mapped to object] []

Hello all,
I had faced some occourrences of this error in a 11.2.0.1 database recently.

ORA-07445: exception encountered: core dump [nstimexp()+45] [SIGSEGV] [ADDR:0x58] [PC:0x7F42ABB] [Address not mapped to object] []

After some investigation I found a match to Bug 3934729.
This issue is originally to matched to Bug 6918493, that is a reintroduction of Bug 2752985 but it’s fixed in 11.2.0.1.
However, on upgrading to 11.2.0.1 it’s a hit on Bug 3934729 which is fixed in 11.2.0.2.

Recommended actions are:
– Upgrade databases do 11.2.0.2 or higher. (best solution, but may require more efforts to validate the upgrade).
– Apply Patch 3934729: RANDOM ORA-07445 CORE DUMPS FROM DATABASE AND ORA-3113 FROM APPLICATION
– Set sqlnet.expire_time=0 (workaround)
– Ignore error.

After some research I decided to apply workaround, based on recommended usage of sqlnet.expire_time (Next weeks post is about this parameter :)).
This might be the root cause for the ORA-03135: connection lost contact and the actual value of this parameter on environment was 1, which is a very low value.

So, check which action is more suitable for your environment!
Hope it helps 🙂

Below some additional informations on my situation:

Continue reading

RHEL: Figuring out CPUs, Cores and Hyper-Threading

Hi all!
It’s a recurrent subject, right? But no one is 100% sure to how figure this out… So, let me quickly show you my way:

– Physical CPUs (sockets):

[root@mysrvr ~]# grep -i "physical id" /proc/cpuinfo | sort -u | wc -l
2
[root@mysrvr ~]# dmidecode -t processor |grep CPU
        Version: Intel(R) Xeon(R) CPU X5570 @ 2.93GHz
        Version: Intel(R) Xeon(R) CPU X5570 @ 2.93GHz

So, 2 physical CPUs.

– Physical Cores

[root@mysrvr ~]# egrep -e "core id" -e ^physical /proc/cpuinfo|xargs -l2 echo|sort -u
physical id : 0 core id : 0
physical id : 0 core id : 1
physical id : 0 core id : 2
physical id : 0 core id : 3
physical id : 1 core id : 0
physical id : 1 core id : 1
physical id : 1 core id : 2
physical id : 1 core id : 3

Each one of Physical Processors has 4 cores.
So, there is two quad-cores. This way, we have 8 cores at all.

– Logical CPUs

[root@mysrvr ~]# grep -i "processor" /proc/cpuinfo | sort -u | wc -l
16

Ok, so we have cores in double.
This means we have Hyper-Threading (technology by Intel Processors).

Not so hard, right?

Those links are similar and quite cool to understand the concepts:
https://access.redhat.com/discussions/480953
https://www.redhat.com/archives/redhat-list/2011-August/msg00009.html
http://www.intel.com/content/www/us/en/architecture-and-technology/hyper-threading/hyper-threading-technology.html

Matheus.