We had an issue with InfluxDBClusterClient an multi-threading : it is not thread safe :(

The thread-safe issues I spotted:

• random.shuffle : calling random.shuffle on the same list from multiple thread could corrupt that list
• removing item from list: two thread may try to remove the same entry from the list
• update host on ONE client: one thread may update client host before another one called orig_func. Therefor when exception occur or no, the variable "h" may no be the real server used.

For first 2 issues, a simple lock around the affected code solve the issue.

For the last issue, it a bit trickier... I ended with a getter (_get_host() and _get_baseurl()), so InfluxDBClusterClient could override them with code that use a thread local variable.

I've also added properties to avoid changing every access to _host or _baseurl, but since those variables should not be used outside influxdb-python code, we could avoid them and directly use the getter.