# Multiple "Users" - Same Session

**URL:** <https://community.gatling.io/t/multiple-users-same-session/1703>\
**Category:** Gatling (Open-Source)\
**Created:** [November 14, 2014, 4:32pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703 "2014-11-14T16:32:37Z")\
**Posts on this page:** 14\
**Page:** 1

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**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 4:32pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/1 "2014-11-14T16:32:37Z")

</div>

I want to simulate something where I have a single session to my website, but multiple things happening to that session at the same time (please save the “why are you doing that?” :).

What I thought I could do was this:

- Execute a /Login
- Grab the “.Authentication” and “ASP.NET\_SessionId” that I got and save them
- Create my actual scenario and set the cookies I stored off and simulated N # of users doing some action  
Is there an easier way to do this?

Please let me know if you need further information.

Thanks,

Levi

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<div class="post-metadata">

**Author:** ![Excilys](https://avatars.discourse-cdn.com/v4/letter/e/8797f3/32.png) [@Excilys](https://community.gatling.io/u/Excilys)\
**Post date:** [November 14, 2014, 4:42pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/2 "2014-11-14T16:42:26Z")

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> I want to simulate something where I have a single session to my website,  
> but multiple things happening to that session at the same time (please save  
> the "why are you doing that?" :).

Good thing you started with this 😉

> Is there an easier way to do this?

I don't think so

You have to way of doing this:

&nbsp;&nbsp;&nbsp;- Don't use Gatling DSL for login in and fetching the session cookie.  
&nbsp;&nbsp;&nbsp;Use whatever HTTP client you like. Gatling ships AsyncHttpClient  
&nbsp;&nbsp;&nbsp;\<[https://github.com/AsyncHttpClient/async-http-client&gt;\](https://github.com/AsyncHttpClient/async-http-client&gt;%5C). Do that in the  
&nbsp;&nbsp;&nbsp;before  
&nbsp;&nbsp;&nbsp;\<[http://gatling.io/docs/2.0.2/general/simulation\_structure.html#hooks&gt](http://gatling.io/docs/2.0.2/general/simulation_structure.html#hooks&gt);  
&nbsp;&nbsp;&nbsp;hook.  
&nbsp;&nbsp;&nbsp;- Use Gatling DSL with a dedicated scenario. This ugly thing here is  
&nbsp;&nbsp;&nbsp;that you'll have to introduce some sort of coordination so that the users  
&nbsp;&nbsp;&nbsp;don't start before you've fetched the session cookie. Depending on your  
&nbsp;&nbsp;&nbsp;Scala skills, a simple delay might be the best solution.

Either way, you'll have to store the cookie in some sort of shared  
threadsafe placeholder such as an AtomicReference, then inject this cookie  
\<[http://gatling.io/docs/2.0.2/http/http\_helpers.html#adding-a-cookie&gt](http://gatling.io/docs/2.0.2/http/http_helpers.html#adding-a-cookie&gt); in  
the "real" users.

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<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 4:54pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/3 "2014-11-14T16:54:38Z")

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Awesome, thanks for the sensible response 😉

I don’t know Scala at all, so the former is probably what I’ll look into to see if I can do what I want to do.

I suppose I can achieve what I’m trying to do by having many users login and repeating the same action N # of times and then logging out.

Thanks again!

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<div class="post-metadata">

**Author:** ![jarrowwx](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jarrowwx](https://community.gatling.io/u/jarrowwx)\
**Post date:** [November 14, 2014, 5:08pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/4 "2014-11-14T17:08:28Z")

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Sometimes how we phrase something creates artificial limits in our understanding of the problem. Instead of asking “why are you doing that” I will ask, “what is the real-world situation that you are trying to simulate?”

I ask because how to move forward depends a great deal on what you want to do after the login is complete, and whether there will be simultaneous requests or not. Will you ever have two real-world users operating under the same web session at the same time? Or are the “multiple things happening” referring to actions taken once the login is completed?

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<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 5:16pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/5 "2014-11-14T17:16:20Z")

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Part of what I’m trying to achieve is admittedly not much of a possibility in the real-world. In my case, our business requirements force of to have to keep a session to a DMS around in Session state on the server (not awesome, I know, but our hands our tied). Out of the box, the object that is stored isn’t thread-safe, however we built a wrapper around it to _make_ it thread-safe.

I wanted to use Gatling to fire off a ton of requests against that same object to vet that but that only works if it’s the same session.

Again, admittedly, that isn’t a real-world scenario as the closer real-world scenario is every session would have its own object in memory, but since we were using Gatling already for other load testing scenarios I thought I’d give this a stab.

In the real world, if the user opened two tabs to the site and fired off two actions it’d be possible for this to happen I suppose.

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<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 8:18pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/6 "2014-11-14T20:18:53Z")

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I’m very close. I’ve gotten the cookies I need in the before like so:

`  
var myCookie = “”  
var sessionCookie = “”

before {  
val client = new AsyncHttpClient()  
val response = client.preparePost(url + “/Login”)  
.addFormParam(“Username”, “SomeUser”)  
.addFormParam(“Password”, “ThePassword”)  
.execute()  
.get()

// I’m sure ugly…but I do not know Scala  
var cookies = response.getCookies().toList  
cookies.foreach(c =\> {  
if(c.getName() == “.MyCookie”) {  
myCookie = c.getValue()  
}

if(c.getName() == “ASP.NET\_SessionId”) {  
sessionCookie = c.getValue()  
}  
})  
}  
`

However I don’t think it’s working. Here is a gist of what I’m doing:

`  
val tryIt =  
exec(addCookie(Cookie(“ASP.NET\_SessionId”, sessionCookie).withDomain("/")))  
exec(addCookie(Cookie(".MyCookie", myCookie).withDomain("/")))  
.exec(http(“go-to-main-page”)  
.get("/")  
.headers(initialPageHeader)  
.check(status.is(200))  
)  
.pause(minWaitMs, maxWaitMs)

.exec( session =\> {  
val time = System.currentTimeMillis  
session.set(“timestamp”, time)  
})  
.exec(  
http(“get-job-id”)  
.get(jobIdURL + “/${timestamp}”)  
.check(status.is(200))  
.check(jsonPath("$.jobId").ofType[Int].saveAs(“jobId”))  
)

val scn = scenario(baseName)  
.during(testTimeSecs) {  
exec(tryIt)  
}

setUp(scn.inject(atOnceUsers(1))).protocols(httpConf)

`

Though it doesn’t appear to be passing along the cookie that I got in the before {} (because I’m getting bad responses like I have not logged in).

I’m sure I’m holding it wrong; what did I do wrong? I tried watching the traffic using Fiddler, but none of it is showing up ☹

Levi

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<div class="post-metadata">

**Author:** ![Excilys](https://avatars.discourse-cdn.com/v4/letter/e/8797f3/32.png) [@Excilys](https://community.gatling.io/u/Excilys)\
**Post date:** [November 14, 2014, 9:56pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/7 "2014-11-14T21:56:51Z")

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val tryIt =  
exec(addCookie(Cookie(“ASP.NET\_SessionId”, sessionCookie).withDomain("/")))  
.exec(addCookie(Cookie(".MyCookie", myCookie).withDomain("/"))) // \<==== YOU FORGOT A LEADING DOT HERE SO IT’S NOT CHAINED  
.exec(http(“go-to-main-page”)

---

<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 9:59pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/8 "2014-11-14T21:59:40Z")

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Sorry, that was a bad paste error when I did the post. I have that in there as it runs, it just doesn’t work and I can’t see what the submission looks like. Is there a way to dump the requests as it’s doing it to see what is in there?

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<div class="post-metadata">

**Author:** ![Excilys](https://avatars.discourse-cdn.com/v4/letter/e/8797f3/32.png) [@Excilys](https://community.gatling.io/u/Excilys)\
**Post date:** [November 14, 2014, 10:01pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/9 "2014-11-14T22:01:02Z")

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[http://gatling.io/docs/2.0.2/general/configuration.html#logback-xml](http://gatling.io/docs/2.0.2/general/configuration.html#logback-xml)

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<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 14, 2014, 10:21pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/10 "2014-11-14T22:21:48Z")

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Ok, so it appears that for whatever reason when I call addCookie it still has the default values and not the ones that the before {} should’ve set them to (even though they’re correctly printed at the top prior to anything else.

Cookies are: 890A75EDFF9FE446D3440F1C3956104DE3306A1B4EF7C41A9428F69A3CC3B00EFA39B2B5974E3B129C18CE4A8111B58932184FBA4C8D2FE37B2D9B7BEEC47C0DE246F1A08A288BF18 E450F775D9F8FA7F9778859FF6F89E326BD76F875F84330C3649E00EBDA4A2690A6718E518408F2  
3no0shixfiisf4s1nqnc0jeq

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<div class="post-metadata">

**Author:** ![Excilys](https://avatars.discourse-cdn.com/v4/letter/e/8797f3/32.png) [@Excilys](https://community.gatling.io/u/Excilys)\
**Post date:** [November 15, 2014, 3:05pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/11 "2014-11-15T15:05:15Z")

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Are you sure your cookies are returned on the same request? Usually, login process involves a redirect, so are you sure you don’t have one cookie on log in POST, and one from the redirect?

Then note that you should close your client.

---

<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 16, 2014, 9:41pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/12 "2014-11-16T21:41:33Z")

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Yep, they’re returned in the POST to Login (that’s what I’m dumping out in the before {} block.

If you have the following code:

`  
class MyLoadTest extends Simulation {

var myCookie = “”  
var sessionCookie = “”

before {  
/\* stuff to get myCookie and sessionCookie \*/  
}

val theTest =  
exec(addCookie(Cookie(".MyCookie", myCookie).withDomain("/")))  
.exec(addCookie(Cookie(“ASP.NET\_SessionId”, sessionCookie).withDomain("/")))  
.exec(http(“initial\_page”).get("/").check(status.is(200))  
)  
.pause(minWaitMs, maxWaitMs)

val scn = scenario(“Test”).during(10) { exec(theTest)}  
setUp(scn.inject(atOnceUsers(1))).protocols(httpConf)  
}

`

When does Scala evaluate the myCookie parameter in exec(addCookie(Cookie(".MyCookie", myCookie).withDomain("/")))? Because it seems like it evaluates that before the before {} actually runs.

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<div class="post-metadata">

**Author:** ![Excilys](https://avatars.discourse-cdn.com/v4/letter/e/8797f3/32.png) [@Excilys](https://community.gatling.io/u/Excilys)\
**Post date:** [November 16, 2014, 9:45pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/13 "2014-11-16T21:45:09Z")

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Oh, right!

Then, directly write the before content inside the simulation (ie, in the constructor).

---

<div class="post-metadata">

**Author:** ![Levi\_Wilson](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Levi\_Wilson](https://community.gatling.io/u/Levi_Wilson)\
**Post date:** [November 16, 2014, 10:19pm UTC](https://community.gatling.io/t/multiple-users-same-session/1703/14 "2014-11-16T22:19:47Z")

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Awesome, works! I’d have tried this before if I actually knew that that was considered the constructor (clearly I know nothing about Scala). Thanks again for your help!