Error handling

[Pedro Santos]

Hello,

I'm having some troubles trying to issue a get that produces an error and
send it to an async channel. Here's what I have:

1 (defn- fetch-response
2 "Fetches the response as an async channel"
3 [url]
4 (try
5 (let [async-stream (http/get (str "http://" url)
{:connection-timeout 5000
6 :request-timeout
5000})
7 c (chan)]
8 (s/connect async-stream c)
9 c)
10 (catch Exception e
11 (print \E))))

I can't catch the exception. It says that the exception is on line 5, don't
know if it's async and I'm not doing this right.

Can someone help me?

Thanks.

[Zach Tellman]

`http/get` returns a deferred value, which will yield the full response.
Since a deferred value is *not* a stream, you can't connect it with
`manifold.stream/connect`. You could do `(d/chain rsp #(async/put! chan
%))` or something in that vein. In either case, I'm not sure why you
wouldn't be able to catch this exception, or how you'd know it was at line
5 if you hadn't caught it. If you can provide the stack trace, that might
help.

Post by Pedro Santos
Hello,
I'm having some troubles trying to issue a get that produces an error and
1 (defn- fetch-response
2 "Fetches the response as an async channel"
3 [url]
4 (try
5 (let [async-stream (http/get (str "http://" url)
{:connection-timeout 5000
6 :request-timeout
5000})
7 c (chan)]
8 (s/connect async-stream c)
9 c)
10 (catch Exception e
11 (print \E))))
I can't catch the exception. It says that the exception is on line 5,
don't know if it's async and I'm not doing this right.
Can someone help me?
Thanks.
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[Pedro Santos]

Hey,

An example of that exception is here:
http://pastebin.com/skeVNzQA
This line:
scavenger.core$fetch_response.invoke(core.clj:45)
Is the http/get.

I ended up using d/on-realized and worked as I expected.
I'm still learning and I don't know if I'm doing something wrong. Do I have
to close the deferred in some way? I'm doing a program that does a LOT of
htt/get, and puts the responses on a channel. The program overflows and on
visualvm I can see that bytes and longs seam to be leaking. Here's the
offending stack trace:


​
Here's my example:
https://github.com/donbonifacio/scavenger/blob/master/src/scavenger/core.clj

Thanks,

Post by Zach Tellman
`http/get` returns a deferred value, which will yield the full response.
Since a deferred value is *not* a stream, you can't connect it with
`manifold.stream/connect`. You could do `(d/chain rsp #(async/put! chan
%))` or something in that vein. In either case, I'm not sure why you
wouldn't be able to catch this exception, or how you'd know it was at line
5 if you hadn't caught it. If you can provide the stack trace, that might
help.

Post by Pedro Santos
Hello,
I'm having some troubles trying to issue a get that produces an error and
1 (defn- fetch-response
2 "Fetches the response as an async channel"
3 [url]
4 (try
5 (let [async-stream (http/get (str "http://" url)
{:connection-timeout 5000
6
:request-timeout 5000})
7 c (chan)]
8 (s/connect async-stream c)
9 c)
10 (catch Exception e
11 (print \E))))
I can't catch the exception. It says that the exception is on line 5,
don't know if it's async and I'm not doing this right.
Can someone help me?
Thanks.
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[Zach Tellman]

I'm sorry for the late response on this, I missed the second half of your
message. No, you don't need to do any resource management, but the
ArrayLongArrays are from Dirigiste statistics aggregators. Only having ~3k
of those isn't cause for concern.

Post by Pedro Santos
Hey,
http://pastebin.com/skeVNzQA
scavenger.core$fetch_response.invoke(core.clj:45)
Is the http/get.
I ended up using d/on-realized and worked as I expected.
I'm still learning and I don't know if I'm doing something wrong. Do I
have to close the deferred in some way? I'm doing a program that does a LOT
of htt/get, and puts the responses on a channel. The program overflows and
on visualvm I can see that bytes and longs seam to be leaking. Here's the
​
https://github.com/donbonifacio/scavenger/blob/master/src/scavenger/core.clj
Thanks,

Post by Zach Tellman
`http/get` returns a deferred value, which will yield the full response.
Since a deferred value is *not* a stream, you can't connect it with
`manifold.stream/connect`. You could do `(d/chain rsp #(async/put! chan
%))` or something in that vein. In either case, I'm not sure why you
wouldn't be able to catch this exception, or how you'd know it was at line
5 if you hadn't caught it. If you can provide the stack trace, that might
help.

Post by Pedro Santos
Hello,
I'm having some troubles trying to issue a get that produces an error
1 (defn- fetch-response
2 "Fetches the response as an async channel"
3 [url]
4 (try
5 (let [async-stream (http/get (str "http://" url)
{:connection-timeout 5000
6
:request-timeout 5000})
7 c (chan)]
8 (s/connect async-stream c)
9 c)
10 (catch Exception e
11 (print \E))))
I can't catch the exception. It says that the exception is on line 5,
don't know if it's async and I'm not doing this right.
Can someone help me?
Thanks.
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Pedro Santos
Home - http://psantos.zi-yu.com
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