Threads locking issue in Hi.UrlRewrite module

[sukhjeevan]

Hi Andy,
We had multiple site outages in past few weeks and accordingly we had registered few tickets with sitecore for each outage to find out the root cause. As per sitecore common issue in each outage is thread locking in Hi.UrlRewrite module. Have a look at attachment for more details.
Hi.UrlRewrite.docx

Please provide some direction on this what code changes would be required to mitigate this issue. Let us know if you need more information on this.

This is Sitecore.NET 8.1 (rev. 160519)

Is there anyway if we can disable this for time being as suggested by sitecore for analysis without having any impact in site
Right now we have set Hi.UrlRewrite.CacheSize value to 100MB. Should we increase this value?

Note: We provide memory dump / SSPG package to sitecore for investigation.

Thanks