Trouble using (/understanding?) lrucache

igor.clark · 2016-08-25T17:20:59+00:00

Hi,At present I implement our own load balancer policy by balancer_by_lua block. I need to access the backend server by some specific URL of backend server a...

Trouble using (/understanding?) lrucache

igor.clark

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
return c:set( k, v )
end

function _M.get( k )
return c:get( k )
end

and call them like this:

local myapp = require "myapp"myapp.set( "hi", "there" )ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor

marklkelly

Hi Igor,

I'm also seeing the same issue (using the lrucache code the same way as you are). From what I've seen, lrucache it should keep data from one request to the next. Did you manage to resolve the issue? If so what was the problem?

Many thanks,

Mark.

On Thursday, 25 August 2016 10:21:02 UTC+1, Igor Clark wrote:

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
return c:set( k, v )
end

function _M.get( k )
return c:get( k )
end

and call them like this:

local myapp = require "myapp"myapp.set( "hi", "there" )ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor

marklkelly

Hi Igor - I actually just resolved the issue I was having. I realised I had lua_code_cache set to off.

On Monday, 3 October 2016 10:54:04 UTC+1, Mark Kelly wrote:

Hi Igor,

I'm also seeing the same issue (using the lrucache code the same way as you are). From what I've seen, lrucache it should keep data from one request to the next. Did you manage to resolve the issue? If so what was the problem?

Many thanks,

Mark.

On Thursday, 25 August 2016 10:21:02 UTC+1, Igor Clark wrote:

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
return c:set( k, v )
end

function _M.get( k )
return c:get( k )
end

and call them like this:

local myapp = require "myapp"myapp.set( "hi", "there" )ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor

igor.clark

Hey Mark, glad to hear you got it sorted. I have lua_code_cache set to off in dev by default, so I'm pretty sure that wasn't my problem. For the record, I couldn't get lrucache doing what I wanted at all, and ended up using ngx.shared.DICT, which suits my needs just as well anyway :-)

Cheers,
Igor

On 03/10/2016 11:01, Mark Kelly wrote:

Hi Igor - I actually just resolved the issue I was having. I realised I had lua_code_cache set to off.

On Monday, 3 October 2016 10:54:04 UTC+1, Mark Kelly wrote:

Hi Igor,

I'm also seeing the same issue (using the lrucache code the same way as you are). From what I've seen, lrucache it should keep data from one request to the next. Did you manage to resolve the issue? If so what was the problem?

Many thanks,

Mark.

On Thursday, 25 August 2016 10:21:02 UTC+1, Igor Clark wrote:

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
return c:set( k, v )
end

function _M.get( k )
return c:get( k )
end

and call them like this:

local myapp = require "myapp"myapp.set( "hi", "there" )ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor

marklkelly

Hi Igor - that’s my point. If you have lua_code_cache set to off, lrucache won’t work - but great you got ngx.shared to work for you anyway.

On 3 October 2016 at 22:44:04, Igor Clark (igor...@gmail.com) wrote:

Hey Mark, glad to hear you got it sorted. I have lua_code_cache set to off in dev by default, so I'm pretty sure that wasn't my problem. For the record, I couldn't get lrucache doing what I wanted at all, and ended up using ngx.shared.DICT, which suits my needs just as well anyway :-)
Cheers,
Igor

On 03/10/2016 11:01, Mark Kelly wrote:

Hi Igor - I actually just resolved the issue I was having. I realised I had lua_code_cache set to off.

On Monday, 3 October 2016 10:54:04 UTC+1, Mark Kelly wrote:

Hi Igor,

I'm also seeing the same issue (using the lrucache code the same way as you are). From what I've seen, lrucache it should keep data from one request to the next. Did you manage to resolve the issue? If so what was the problem?

Many thanks,

Mark.

On Thursday, 25 August 2016 10:21:02 UTC+1, Igor Clark wrote:

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
return c:set( k, v )
end

function _M.get( k )
return c:get( k )
end

and call them like this:

local myapp = require "myapp" myapp.set( "hi", "there" ) ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor

igor.clark

Oh!!!! I *see*. Well, that makes perfect sense now that you say it. Gah.

Thanks very much Mark for solving that :-)

On 03/10/2016 23:32, Mark Kelly wrote:

Hi Igor - that’s my point. If you have  lua_code_cache set to off, lrucache won’t work - but great you got ngx.shared to work for you anyway.

On 3 October 2016 at 22:44:04, Igor Clark (igor...@gmail.com) wrote:

Hey Mark, glad to hear you got it sorted. I have lua_code_cache set to off in dev by default, so I'm pretty sure that wasn't my problem. For the record, I couldn't get lrucache doing what I wanted at all, and ended up using ngx.shared.DICT, which suits my needs just as well anyway :-)

Cheers,
Igor

On 03/10/2016 11:01, Mark Kelly wrote:

Hi Igor - I actually just resolved the issue I was having. I realised I had lua_code_cache set to off.

On Monday, 3 October 2016 10:54:04 UTC+1, Mark Kelly wrote:

Hi Igor,

I'm also seeing the same issue (using the lrucache code the same way as you are). From what I've seen, lrucache it should keep data from one request to the next. Did you manage to resolve the issue? If so what was the problem?

Many thanks,

Mark.

On Thursday, 25 August 2016 10:21:02 UTC+1, Igor Clark wrote:

Hi folks,

Trying to use lrucache to keep some lua term data in memory. I have the example from the docs running fine.

If I add these functions to the myapp module:

function _M.set( k, v )
    return c:set( k, v )
end

function _M.get( k )
    return c:get( k )
end

and call them like this:

local myapp = require "myapp" myapp.set( "hi", "there" ) ngx.say( myapp.get( "hi" ) )

it works fine in the context of one request, but if i remove the "set()" call and hit the endpoint again, it just says "nil".

The doc says " your cache is always limited to the current OS process (like the current nginx worker process)" - but this happens even when I set "worker_processes 1;" in the main nginx.conf.

What am I doing wrong, or perhaps not understanding correctly? Should it not keep the data from one request to the next? What's the use case, if not?

Thanks for any help, I'm scratching my head at the moment!

Cheers,

Igor