RE: Tomcat config with virtual threads

Thanks Chris, Mark.

-----Original Message-----
From: Christopher Schultz <[email protected]> 
Sent: Monday, February 2, 2026 6:29 PM
To: [email protected]
Subject: Re: Tomcat config with virtual threads

Joan,

On 2/2/26 8:54 AM, Mark Thomas wrote:
> On 02/02/2026 10:16, [email protected] wrote:
>> Hello,
>>
>>
>> I'm working with Tomcat 10.1.4x and java25, our application is 
>> extensively using virtual threads. I enable them in tomcat by simply 
>> using
>> 'useVirtualThreds: true'.
>>
>>
>> It's working perfectly, by I was wondering if parameters like 
>> maxThreads, minSpareThreads, acceptCount, etc has any effect when 
>> working with virtual threads.
>>
>>
>> For instance, I set maxThreads = minSpareThreads = acceptCount = 1, 
>> and nothing seems to change (for worse).
> 
> maxThreads - no effect
> 
> minSpareThreads - no effect
> 
> In short, anything that you can set on an Executor will have no effect.
> 
> acceptCount will have an effect (if your OS pays any attention to the 
> setting - not all do).

Note that this setting has nothing to do with threads. Instead, it's a hint to the OS's network stack to allow connections to pile-up in a queue.

> The setting likely to have the most impact in this area will be 
> maxConnections. If set, once you hit maxConnections then acceptCount 
> comes into play.

Another setting that has nothing to do with threads. The <Connector> contains settings that affect the <Executor> that gets auto-created if you use a <Connector> without specifying one, and other settings that are unrelated.

If you separate your <Connector> into <Connector> and <Executor> it may become easier for you reason about what will and will not affect your virtual-threads-based JVM.

-chris


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