Are empty $_SESSIONs possible?
Posted: Sat Dec 10, 2005 5:00 am
dear all,
i'm currently conducting an online survey and had a problem with empty $_SESSION variables.
the survey in question would be this: Forecasting Survey
all data that is not generated through user interaction, eg. selecting options, is stored in session variables and passed back to the script before saving to a text/csv file.
the second day into the study, one clever guy "stress-tested" the script and played roughly 50 consecutive rounds with round times of less than 4 seconds (between page display and submission) in some cases.
after this "incident", the script started to generate empty values as other people started to play at the same time (3 times). namely the data that is stored in session variables. everything else, eg. the $_POST variables worked fine. since then, as people interacted "normally" with the script, nothing similar happened.
my questions are the following:
- what could've caused the empty values? is it because the script "overheated"? are there limitations to session variables when under stress, i.e. multiple sessions at the same time and fast changes in session variables?
and
- are there limitations to using flat files for this? would we be better off using MySQL?
thanks for sharing your thoughts.
-pascal
i'm currently conducting an online survey and had a problem with empty $_SESSION variables.
the survey in question would be this: Forecasting Survey
all data that is not generated through user interaction, eg. selecting options, is stored in session variables and passed back to the script before saving to a text/csv file.
the second day into the study, one clever guy "stress-tested" the script and played roughly 50 consecutive rounds with round times of less than 4 seconds (between page display and submission) in some cases.
after this "incident", the script started to generate empty values as other people started to play at the same time (3 times). namely the data that is stored in session variables. everything else, eg. the $_POST variables worked fine. since then, as people interacted "normally" with the script, nothing similar happened.
my questions are the following:
- what could've caused the empty values? is it because the script "overheated"? are there limitations to session variables when under stress, i.e. multiple sessions at the same time and fast changes in session variables?
and
- are there limitations to using flat files for this? would we be better off using MySQL?
thanks for sharing your thoughts.
-pascal