Re: [racket-users] DrRacket 6.5 + OS X El Capitan = slow execution
Hello, Robby! Thank you for your reply. I have done quoting out register-collecting-blit and the flashing gc icon disappeared. But the feeling of slowness is still present, I afraid. I am timing execution with cursor blinks: it blinks once or twice in DrRacket 6.5 while (+ 1 1) execution, but in DrRacket 6.2.1 this code executes almost immediately. But more complex expressions aren’t executed proportionally slower - the same one blink. P.S. May be it is just some strange cognitive effect. Is there a way to measure time from run button pressing to printing execution results precisely and objectively somehow? > On 16 Aug 2016, at 02:52, Robby Findler wrote: > > Hi Ivan: here is another experiment to try. What happens if you follow > these steps: > > - start DrRacket > - open "Language" menu's "Choose Language..." menu item > - select "The Racket Language" (click ok to close the dialog) > - select the "File" menu's "Open Require Path..." menu item > - type "fr/pr/frame" in the dialog and hit return > - search for "(register-c" in that file. You should see a call to > register-collecting-blit around line 912 or so > - put a quote in front of it (to stop it from executing), the code > should be like this: > > '(register-collecting-blit gc-canvas >0 0 >(send onb get-width) >(send onb get-height) >onb offb) > > - save the file and restart DrRacket > > At this point, redo your experiment that was very slow earlier (you > may need to switch back to one of the teaching languages in the > "Choose Language..." dialog to fully replicate your experiment). > > If the steps above worked, you will have disabled the flashing gc > icon, so if you were using that to time your DrRacket, then use > something else (a watch, maybe). > > Thanks in advance! > > Robby -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Re: HtDP 2e
Ohne hast aber ohne rast;-) Congratulations and thanks for this great work! Hope HtDC is the next huge step. -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] DrRacket 6.5 + OS X El Capitan = slow execution
Do you see any change if you start DrRacket in Terminal with env PLT_INCREMENTAL_GC=n /Applications/Racket\ v6.5/bin/drracket ? (That's assuming that Racket is installed as "Racket v6.5" in the "Applications" folder.) As of v6.4, DrRacket uses an incremental GC mode to reduce pauses while programs are being edited. Incremental mode can slow down bulk work, though, such as starting a program. The GC's mode adapts to the current workload, but adapting takes a little while, and running a program right after typing is one of the transition cases. In contrast, clicking the "Run" button repeatedly should shift to a non-incremental mode after a couple of clicks. Thanks! Matthew At Tue, 16 Aug 2016 18:16:13 +1000, Ivan Kuzmin wrote: > Hello, Robby! Thank you for your reply. > > I have done quoting out register-collecting-blit and the flashing gc icon > disappeared. But the feeling of slowness is still present, I afraid. > > I am timing execution with cursor blinks: it blinks once or twice in DrRacket > 6.5 while (+ 1 1) execution, but in DrRacket 6.2.1 this code executes almost > immediately. > But more complex expressions aren’t executed proportionally slower - the same > one blink. > > P.S. May be it is just some strange cognitive effect. Is there a way to > measure time from run button pressing to printing execution results precisely > and objectively somehow? > > > On 16 Aug 2016, at 02:52, Robby Findler wrote: > > > > Hi Ivan: here is another experiment to try. What happens if you follow > > these steps: > > > > - start DrRacket > > - open "Language" menu's "Choose Language..." menu item > > - select "The Racket Language" (click ok to close the dialog) > > - select the "File" menu's "Open Require Path..." menu item > > - type "fr/pr/frame" in the dialog and hit return > > - search for "(register-c" in that file. You should see a call to > > register-collecting-blit around line 912 or so > > - put a quote in front of it (to stop it from executing), the code > > should be like this: > > > > '(register-collecting-blit gc-canvas > >0 0 > >(send onb get-width) > >(send onb get-height) > >onb offb) > > > > - save the file and restart DrRacket > > > > At this point, redo your experiment that was very slow earlier (you > > may need to switch back to one of the teaching languages in the > > "Choose Language..." dialog to fully replicate your experiment). > > > > If the steps above worked, you will have disabled the flashing gc > > icon, so if you were using that to time your DrRacket, then use > > something else (a watch, maybe). > > > > Thanks in advance! > > > > Robby -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] racket/db, creating queries from fetched values
Hi!
I'm a new user of Racket and I am trying to make a simple application which
interfaces a MySQL database.
Fetching the data is quite straightforward, but I am having trouble coming up
with a reasonable way to insert the data back into database. Basically the
fetched vector contains many different data types, but I haven't found an easy
way to serialize them back to a string for SQL queries.
SELECT now();
Would result in a vector like this
(vector (sql-timestamp 2016 8 16 17 1 39 0 #f))
What would be a reasonable way to serialize this to "2016-08-16 17:01:39", for
example:
INSERT INTO x VALUES ("2016-08-16 17:01:39")
This question is not particular to serializing a sql-timestamp, but any data
type.
--
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 racket-users+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] DrRacket 6.5 + OS X El Capitan = slow execution
On Tue, Aug 16, 2016 at 3:16 AM, Ivan Kuzmin wrote: > P.S. May be it is just some strange cognitive effect. Is there a way to > measure time from run button pressing to printing execution results precisely > and objectively somehow? Probably it is real, but you're right that doing this a bit more objectively is a good idea! To do that, use the "Open Require Path..." menu item to open "drracket/private/unit.rkt", search for these two lines: (define/public (execute-callback) (when (send execute-button is-enabled?) and add, just below them on its own line: (printf "Run: ~s\n" (current-process-milliseconds)) Then, using the same menu item to open "drracket/private/rep.rkt", search for this line: (define/public (insert-prompt) and insert just below it a similar line: (printf "Prompt: ~s\n" (current-process-milliseconds)) It should be the case that you'll be able to take two consecutive printouts and use subtraction to get a good estimate of how much time was used. Thanks for your help looking into this! Robby -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] racket/db, creating queries from fetched values
On 8/16/2016 10:04 AM, ksiimson wrote:
Hi!
I'm a new user of Racket and I am trying to make a simple application which
interfaces a MySQL database.
Fetching the data is quite straightforward, but I am having trouble coming up
with a reasonable way to insert the data back into database. Basically the
fetched vector contains many different data types, but I haven't found an easy
way to serialize them back to a string for SQL queries.
SELECT now();
Would result in a vector like this
(vector (sql-timestamp 2016 8 16 17 1 39 0 #f))
What would be a reasonable way to serialize this to "2016-08-16 17:01:39", for
example:
INSERT INTO x VALUES ("2016-08-16 17:01:39")
This question is not particular to serializing a sql-timestamp, but any data
type.
You don't need to convert the values to text. You want to use query
parameters instead.
MySQL queries use "?" for parameter placeholders, so you want to do
something like:
(query-exec dbc "INSERT INTO x ( a_datetime, an_integer, a_float )
VALUES (?,?,?)"
"2016-08-16 17:01:39"
42
3.14159 )
The arguments to *query-exec* (or *query*, see below) need to match the
order and expected types of the parameter placeholders in the query
string, but you don't need to convert arguments to text or splice them
into the string. In general you don't want to do that anyway because
that is how SQL injection flaws can creep into your code. There are
occasions when deficiencies in the SQL syntax actually will force you to
splice things directly into the query string, but you should avoid doing
so as much as possible. Use query parameters unless you really have no
choice.
If the argument type isn't correct you need to cast or convert it to the
right type in the query string: e.g., to pass a datetime to a query
that expects just a date:
(define the-date (sql-timestamp 2016 8 16 17 1 39 0 #f))
(query-exec dbc "INSERT INTO x ( a_datetime ) VALUES ( cast( ? as date ) )"
the-date )
Note: *query-exec* doesn't return status. If you need to know how many
rows were affected, use *query *instead. For more information see
http://docs.racket-lang.org/db/query-api.html?q=query
http://docs.racket-lang.org/db/sql-types.html?q=mysql#%28part._mysql-types%29
Hope this helps,
George
--
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 racket-users+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] racket/db, creating queries from fetched values
On 8/16/2016 12:33 PM, Kristjan Siimson wrote: Ah, yes. I should of have clarified that I'm trying to build queries, but I don't want them to be executed. I guess, alternatively, I could solve it by creating a blackhole database and viewing the executed queries from the general log. If Im going with that approach, then this will help me to go in the right direction. Thanks for answering! :-) Do you mean "prepared" queries? Or something else? Prepared queries are almost the same as parameterized: (define stmt (prepare dbc "INSERT INTO x VALUES( ?, ? )" )) (bind-prepared-statement stmt param-list ) (query-exec dbc stmt ) (bind-prepared-statement stmt another-param-list ) (query-exec dbc stmt ) A prepared query is compiled once and the code is cached on the server for reuse until the connection is closed or the query is explicitly dropped. The downside to this is that the prepared query uses a generic execution plan ... its parameters are not known at compile time so the query can't be optimized based on particular parameter values (which affects usage of auxiliary indexes). Also be aware that prepared queries are tied to specific connections, so connection sharing/pooling may be problematic. There also are server side limits on the number of prepared queries allowed - both per connection and globally. Normal queries are compiled, executed and quickly discarded. In reality the code is cached for a short time in case the *exact* same query (including parameter values) is submitted again. The same query string paired with different parameters will be compiled as a new query. George -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Linux packages?
Would be great if it would be packages to download from racket-Lang. At least for the major dists. -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Re: Linux packages?
On Tuesday, August 16, 2016 at 1:17:27 PM UTC-5, Andreas Olsson wrote: > Would be great if it would be packages to download from racket-Lang. At least > for the major dists. There's a PPA for ubuntu(https://launchpad.net/~plt/+archive/ubuntu/racket) which is how I got it. Maybe they could just put it on the downloads page? -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] Re: Linux packages?
If there was packages for the major dists like fedora, ubuntu and suse on the racket homepage it would be easier for people to get. It would help racket becoming a little more known and used. -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
