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Description
Reading from more than ~1000 goroutines simultaneously fails with an error "unable to open database file". Test program is attached. You can tweak maxRoutines to see the normal/broken behavior, on my local tests everything works fine until about 1000 goroutines.
package main
import (
"database/sql"
"fmt"
"log"
"math/rand"
"os"
"sync"
_ "github.com/mattn/go-sqlite3"
)
const (
maxKeys = 20
maxRoutines = 5000
)
func main() {
// Create DB.
os.Remove("./test.db")
destDb, err := sql.Open("sqlite3", "./test.db")
if err != nil {
log.Fatal(err)
}
defer destDb.Close()
destDb.Ping()
// Create table.
_, err = destDb.Exec("create table test(id int, value text)")
if err != nil {
log.Fatal(err)
}
// Write 20 values.
for i := 0; i < maxKeys; i++ {
_, err = destDb.Exec(fmt.Sprintf("insert into test values(%d, 'random_value')", i))
if err != nil {
log.Fatal(err)
}
}
// Now test.
stressTest(destDb)
fmt.Printf("Success!\n")
}
func stressTest(db *sql.DB) {
// Read values from all of these simultaneously.
var wg sync.WaitGroup
for i := 0; i < maxRoutines; i++ {
wg.Add(1)
go read(i, db, &wg)
}
wg.Wait()
}
func read(num int, db *sql.DB, wg *sync.WaitGroup) {
defer wg.Done()
_, err := db.Query(fmt.Sprintf("select value from test where id=%d", rand.Intn(maxKeys)))
if err != nil {
fmt.Printf("Goroutine %d failed read : %v\n", num, err)
}
}Metadata
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