The 1040 error is from MySQL. One thing to check is if there is a connection limit on the MySQL side, and what it happens to be. If you are quick at dispatching operations it may be that you will end up in a situation where you hit the limit as you increase load.
My bet though is on what Naoki INADA writes. Also note that MySQL is able to take an outright insanely high amount of simultaneous connections compared to e.g., PostgreSQL. You are often better off having a smaller postgres pool and keeping it a well-defined size not reclaiming idle connections (rule of thumb was 2xCores on postgres though it has been years since I last needed to tune one) On Mon, May 29, 2017 at 4:01 PM Daniel Theophanes <kardia...@gmail.com> wrote: > If you can provide a running example that demonstrates how the > database/sql package + driver opens more connections then > db.SetMaxOpenConns specify, then it can be considered a bug and should be > reported to https://golang.org/issue . > > > On Thursday, May 25, 2017 at 7:25:48 AM UTC-7, viridi...@gmail.com wrote: >> >> Hi All, >> >> I'm using go-sql-driver/mysql in my web-application. Each API call has >> about 3-4 queries it performs. Which are all insert or fetch single row >> queries like: >> >> _, err := db.Exec(query, parms) >> >> if err != nil { >> log.Fatal(err) >> >> } >> >> err := db.QueryRow(query, params).Scan(&data) >> if err != nil { >> log.Fatal(err) >> >> } >> >> I have also the following configuration >> db.SetMaxOpenConns(50) >> db.SetMaxIdleConns(20) >> >> I am making a call to 2 api's which have a combined db call of 8 >> queires. When I make a call with 120 concurrent users with a ramp up time >> of 5 sec i get Error 1040: Too many connections. >> >> it works fine for up to 90-100 users. My question is why does the db not >> re-using the connections or why does it not release the connections soon >> enough? >> >> As both Exec and QueryRow are supposed to release connections immediately >> since I use Scan soon after, shouldn't the number of connections it support >> be more in number than just double? >> >> Any insight is appreciated. >> >> >> >> >> >> -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
