Hbase Regionserver doesn't start

[#1]

Please help me out,

Unable to figure out what the problem is while starting regionserver, It exits with following message

starting regionserver, logging to /var/log/hbase/hbase-root-regionserver-ip-172-31-19-88.out
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000300000000, 20401094656, 0) failed; error='Cannot allocate memory' (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 20401094656 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /var/log/hbase/hs_err_pid31016.log

below are the free -m o/p:

            total |used |free|shared|buffers|cached
Mem:         68555 |21134 |47420|0|181 |14850 -/+ buffers/cache:       6102      62452
Swap:            0          0          0

I am not not sure if it is a Java Error or OS error

Below is are system configs:

Ram : 70gb
os: Redhat centos 6.7
Ambari : 2.2.2  
HDP : 2.4.2
Java Version (Ambari): 1.8.0_40 

[#2]

Thank you for the response,

Tried that one but seem to have no impact

[#3 · Accepted solution]

Here is the solution

Hawq installation have caused a change to /etc/sysctl.conf

Had to change it back to default value and got rid of all the OOM errors.

vm.overcommit_memory=2

Had to change to default value 
vm.overcommit_memory=0