RFR: 8185005: Improve performance of ThreadMXBean.getThreadInfo(long ids[], int maxDepth)

[David Holmes]

Hi Daniil,

The definition and use of this hashtable (yet another hashtable 
implementation!) will need careful examination. We have to be concerned 
about the cost of maintaining it when it may never even be queried. You 
would need to look at footprint cost and performance impact.

Unfortunately I'm just about to board a plane and will be out for the 
next few days. I will try to look at this asap next week, but we will 
need a lot more data on it.

Thanks,
David

On 28/06/2019 6:31 pm, Daniil Titov wrote:
> Please review the change that improves performance of ThreadMXBean MXBean methods returning the
> information for specific threads. The change introduces the thread table that uses ConcurrentHashTable
> to store one-to-one the mapping between the thread ids and JavaThread objects and replaces the linear
> search over the thread list in ThreadsList::find_JavaThread_from_java_tid(jlong tid) method with the lookup
> in the thread table.
> 
> Testing: Mach5 tier1,tier2 and tier3 tests successfully passed.
> 
> Webrev: https://cr.openjdk.java.net/~dtitov/8185005/webrev.01/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8185005
> 
> Thanks!
> 
> Best regards,
> Daniil
> 
> 
>