Any Erlang “hierarchical timing wheel” library?

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Any Erlang “hierarchical timing wheel” library?

Frank Muller
Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank

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Re: Any Erlang “hierarchical timing wheel” library?

Frank Muller
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank

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Re: Any Erlang “hierarchical timing wheel” library?

Torben Hoffmann
This is the nearest I can think of:
https://github.com/fra/ecron/blob/master/README.md

Cheers,
Torben
On Tue, 18 Dec 2018 at 06:17, Frank Muller <[hidden email]> wrote:
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank
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Re: Any Erlang “hierarchical timing wheel” library?

Vans S
Why dont you write your own, since this is a special use case anyways that has a ton of implementations, there is no way youl find an implemenation that will fully satisfy you. Its quite simple too, Hashed and Hierarchical Timing Wheels, scheme #2 here will be VERY performant on erlang.  an ordered_set mnesia table, using dirty_next to get the first element each 1-10ms to check if a timer is ready to pop. Then spawn a new process and pass the event for handling to it.




On Tuesday, December 18, 2018, 1:22:44 a.m. EST, Torben Hoffmann <[hidden email]> wrote:


This is the nearest I can think of:
https://github.com/fra/ecron/blob/master/README.md

Cheers,
Torben
On Tue, 18 Dec 2018 at 06:17, Frank Muller <[hidden email]> wrote:
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank
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Re: Any Erlang “hierarchical timing wheel” library?

Frank Muller
Hi Vans

I always ask first before re-implementing the wheel. The link is very good (did my home work and read almost all papers on the subject before asking).

@Vans: thanks for implementation hints.
What do you suggest for persistency? Is mnesia capable of handling millions terms?

Best
/Frank

Why dont you write your own, since this is a special use case anyways that has a ton of implementations, there is no way youl find an implemenation that will fully satisfy you. Its quite simple too, Hashed and Hierarchical Timing Wheels, scheme #2 here will be VERY performant on erlang.  an ordered_set mnesia table, using dirty_next to get the first element each 1-10ms to check if a timer is ready to pop. Then spawn a new process and pass the event for handling to it.




On Tuesday, December 18, 2018, 1:22:44 a.m. EST, Torben Hoffmann <[hidden email]> wrote:


This is the nearest I can think of:
https://github.com/fra/ecron/blob/master/README.md

Cheers,
Torben
On Tue, 18 Dec 2018 at 06:17, Frank Muller <[hidden email]> wrote:
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank
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Re: Any Erlang “hierarchical timing wheel” library?

Vans S

Mnesia would handle millions of disk persistented terms.  Assuming in this case youl only be calling :mnesia.next or dirty_next, and comparing the time on it, itl be super low latency and fast.  Inserts are also very fast into ordered_set.  
On Tuesday, December 18, 2018, 10:01:53 a.m. EST, Frank Muller <[hidden email]> wrote:


Hi Vans

I always ask first before re-implementing the wheel. The link is very good (did my home work and read almost all papers on the subject before asking).

@Vans: thanks for implementation hints.
What do you suggest for persistency? Is mnesia capable of handling millions terms?

Best
/Frank

Why dont you write your own, since this is a special use case anyways that has a ton of implementations, there is no way youl find an implemenation that will fully satisfy you. Its quite simple too, Hashed and Hierarchical Timing Wheels, scheme #2 here will be VERY performant on erlang.  an ordered_set mnesia table, using dirty_next to get the first element each 1-10ms to check if a timer is ready to pop. Then spawn a new process and pass the event for handling to it.




On Tuesday, December 18, 2018, 1:22:44 a.m. EST, Torben Hoffmann <[hidden email]> wrote:


This is the nearest I can think of:
https://github.com/fra/ecron/blob/master/README.md

Cheers,
Torben
On Tue, 18 Dec 2018 at 06:17, Frank Muller <[hidden email]> wrote:
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank
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Re: Any Erlang “hierarchical timing wheel” library?

Roger Lipscombe-2
In reply to this post by Frank Muller
This isn't particularly applicable, because you're looking for an implementation in Erlang, rather than an implementation *in* Erlang, but if you're interested, there's a timer wheel implementation in erts/emulator/beam/time.c. It's not directly usable as a timer wheel from Erlang (or from a NIF, which is where my interest originated).

For comparison, libcurl appears to use a splay tree for its timers -- or did, the last time I looked.

On Tue, 18 Dec 2018 at 15:01, Frank Muller <[hidden email]> wrote:
Hi Vans

I always ask first before re-implementing the wheel. The link is very good (did my home work and read almost all papers on the subject before asking).

@Vans: thanks for implementation hints.
What do you suggest for persistency? Is mnesia capable of handling millions terms?

Best
/Frank

Why dont you write your own, since this is a special use case anyways that has a ton of implementations, there is no way youl find an implemenation that will fully satisfy you. Its quite simple too, Hashed and Hierarchical Timing Wheels, scheme #2 here will be VERY performant on erlang.  an ordered_set mnesia table, using dirty_next to get the first element each 1-10ms to check if a timer is ready to pop. Then spawn a new process and pass the event for handling to it.




On Tuesday, December 18, 2018, 1:22:44 a.m. EST, Torben Hoffmann <[hidden email]> wrote:


This is the nearest I can think of:
https://github.com/fra/ecron/blob/master/README.md

Cheers,
Torben
On Tue, 18 Dec 2018 at 06:17, Frank Muller <[hidden email]> wrote:
Really, no library out there?

/Frank

Hi there 

I am looking for any Erlang implementation of a “hierarchical timing wheel” with disk persistency (if possible)?

I need to handle a very large number of timers (around 10 million events) in my app. Each timer will trigger an associated MFA event. 

I’ve one special case: some events can be triggered after a long period of time (ex. 2 years). The rest of the timers can be considered short (in minutes, hours or days at max). That’s why “hierarchical timing wheel” can solve this special case.

Any help/idea/link appreciated.

Thank you
/Frank
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