Thanks David, that makes a little sense also because it often happens after there has been no activity on the server for a while. If it is a stale handle, is there something I can do about it?
I got rid of the string-join, although I think I was using bind params already -- I did not join strings that were variable, all variables get passed via "?" in the string itself. It might be because I do `(number->string (random 1000000)), which is because it means I don't have to convert it to strings every time I put it in the webpage. Cheers, Marc On Wed, Apr 5, 2017 at 1:25 PM, David Storrs <[email protected]> wrote: > I'm guessing here, but these lines: > > /usr/share/racket/pkgs/db-lib/db/private/mysql/message.rkt:417:0: > parse-packet > /usr/share/racket/pkgs/db-lib/db/private/mysql/connection.rkt:105:4: > recv* method in connection% > > suggest to me that the issue is: > > 1) The connection handle is stale or not established > > 2) It's failing to make the connection before the initial call is > made, so it receives something that isn't a packet back (my guess > would be #f, but that's purely a guess). > > 3) The connection then finishes being made so the second call works. > > > The reason it works on localhost is that the DB is instantly available > with no network latency and your handles are not stale. > > As an aside, I would suggest using bind params for your SQL instead of > assembling it as a string. It will be faster, might fix your problem, > and will be substantially more secure depending on where your data is > coming from. It will also allow the handle to cache statements for > future use. The only change you need is to get rid of the > string-append: > > (query-exec > dbc > "INSERT INTO participant (subscribed, next_matrix, > completion_code, comprehension_incorrect, comprehension_question) > VALUES (1, 1, ?, 0, 0)" > (random 1000000)) > > > Hope this helps, > > Dave > > On Wed, Apr 5, 2017 at 12:08 PM, Marc Kaufmann > <[email protected]> wrote: > > Hi all, > > > > I have the following code that occasionally throws an error when called, > but definitely not always: > > > > " > > (define (study-add-participant! a-study) > > (displayln-date) > > (define dbc (study-db a-study)) > > (displayln "Inserting new participant...") > > (query-exec > > dbc > > (string-join > > '( > > "INSERT INTO participant (subscribed, next_matrix, > completion_code, comprehension_incorrect, comprehension_question)" > > "VALUES (1, 1, ?, 0, 0)")) > > (number->string (random 1000000))) > > (displayln "New participant inserted. Getting id of new > participant...") > > ... ; More stuff > > " > > > > Sometimes I hit the following error, but never if I refresh the page > that calls 'study-add-participant!, and usually I don't hit the error at > all. > > > > " > > Servlet (@ /tutorial) exception: > > io:read-le-intN: internal error; > > unexpected eof; got #<eof> > > > > context...: > > /usr/share/racket/collects/db/private/generic/interfaces.rkt:209:0: > error*9 > > /usr/share/racket/pkgs/db-lib/db/private/mysql/message.rkt:417:0: > parse-packet > > /usr/share/racket/pkgs/db-lib/db/private/mysql/connection.rkt:105:4: > recv* method in connection% > > .../more-scheme.rkt:261:28 > > /usr/share/racket/collects/db/private/generic/common.rkt:276:13 > > /usr/share/racket/collects/db/private/generic/../../../ > racket/private/more-scheme.rkt:261:28 > > [repeats 1 more time] > > /usr/share/racket/collects/db/private/generic/functions.rkt:141:0: > compose-statement > > /usr/share/racket/collects/db/private/generic/functions.rkt:216:0: > query-exec > > /home/marc/mturk/model.rkt:99:0: study-add-participant! > > /home/marc/mturk/pages.rkt:563:0: tutorial > > /usr/share/racket/collects/racket/contract/private/arrow- > higher-order.rkt:342:33 > > [repeats 1 more time] > > /usr/share/racket/pkgs/web-server-lib/web-server/ > dispatchers/dispatch-servlets.rkt:58:2 > > /usr/share/racket/collects/racket/contract/private/arrow- > higher-order.rkt:342:33 > > [repeats 1 more time] > > ... > > " > > > > From the logs, I know that this happens in the query-exec, since I see > the first `displayln message, but not the second one. What I do not > understand is how I can hit the message sometimes but not other times? What > (hidden?) state is there that is changing and sometimes causes the > io:read-le-intN to fail? > > > > If it helps with diagnosing: > > > > - The query did not get run successfully on the database. > > - The query itself is correct, since it succeeds the second time, and > since it succeeded yesterday. Thus, it's not that I am addressing a missing > database or anything. > > - I have never yet hit this error when running the code on localhost for > testing and development. This is on the live server. > > > > I am happy to provide more logs or run commands to figure out what is > going on, but unfortunately I cannot even replicate the bug reliably (I hit > it 4 times so far. > > > > Thanks, > > Marc > > > > -- > > You received this message because you are subscribed to the Google > Groups "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected]. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
