Singleton design pattern

[Guest]

Hello All,

If I create a class based on Singleton design pattern, are the methods in
this class thread-safe?

Consider the following class:

Public class Singleton
{

public int Add(int a, int b)
{

}

}

If suppose I have a request A which calls the method with params as 1 and 2
and another request simultaneously calls the method with params as 3 and 4

Is there a possibility that the params are overrided as follows

--> Request A calls the method with params as 1 and 4
--> Request A calls the method with params as 3 and 2

Thanks for your suggestions!!!

 

[bruce barker]

it depends on the code. if your class contains no shareded variables, and
calls no unmanged code, it will be threadsafe.

-- bruce (sqlwork.com)


| Hello All,
|
| If I create a class based on Singleton design pattern, are the methods in
| this class thread-safe?
|
| Consider the following class:
|
| Public class Singleton
| {
|
| public int Add(int a, int b)
| {
|
| }
|
| }
|
| If suppose I have a request A which calls the method with params as 1 and
2
| and another request simultaneously calls the method with params as 3 and 4
|
| Is there a possibility that the params are overrided as follows
|
| --> Request A calls the method with params as 1 and 4
| --> Request A calls the method with params as 3 and 2
|
| Thanks for your suggestions!!!

 

[Scott Allen]

Parameters are passed to a method using a stack. Each thread maintains it's
own stack so that the parameters are not shared among threads.

See:

http://odetocode.com/Articles/313.aspx
http://odetocode.com/Articles/314.aspx

 

[Guest]

1) Shared variables
2) Unmanaged code

Are these the necessary and sufficient conditions for singleton class
methods to be thread-safe?

 

[Matt Berther]

Hello Scott,

Thanks for the articles, Scott... This debate came up at work the other day.
Your articles will help to prove my case. :=)

 

[bruce barker]

these are the only cases that cause a singleton to not be threadsafe.

1) you can use unmaned code if you know its threadsafe
2) you can use shared/statics if you sync, and you expect the same data
across all threads.

-- bruce (sqlwork.com)




| 1) Shared variables
| 2) Unmanaged code
|
| Are these the necessary and sufficient conditions for singleton class
| methods to be thread-safe?
|
| "bruce barker" wrote:
|
| > it depends on the code. if your class contains no shareded variables,
and
| > calls no unmanged code, it will be threadsafe.
| >
| > -- bruce (sqlwork.com)
| >
| >
| > | > | Hello All,
| > |
| > | If I create a class based on Singleton design pattern, are the methods
in
| > | this class thread-safe?
| > |
| > | Consider the following class:
| > |
| > | Public class Singleton
| > | {
| > |
| > | public int Add(int a, int b)
| > | {
| > |
| > | }
| > |
| > | }
| > |
| > | If suppose I have a request A which calls the method with params as 1
and
| > 2
| > | and another request simultaneously calls the method with params as 3
and 4
| > |
| > | Is there a possibility that the params are overrided as follows
| > |
| > | --> Request A calls the method with params as 1 and 4
| > | --> Request A calls the method with params as 3 and 2
| > |
| > | Thanks for your suggestions!!!
| >
| >
| >

 

[Scott Allen]

Cool! I'm happy to know they are useful!