lotus/lib/ulimit/ulimit.go

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package ulimit
// from go-ipfs
import (
"fmt"
"os"
"strconv"
"syscall"
logging "github.com/ipfs/go-log"
)
var log = logging.Logger("ulimit")
var (
supportsFDManagement = false
// getlimit returns the soft and hard limits of file descriptors counts
getLimit func() (uint64, uint64, error)
// set limit sets the soft and hard limits of file descriptors counts
setLimit func(uint64, uint64) error
)
// minimum file descriptor limit before we complain
const minFds = 2048
// default max file descriptor limit.
const maxFds = 16 << 10
// userMaxFDs returns the value of LOTUS_FD_MAX
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func userMaxFDs() uint64 {
// check if the LOTUS_FD_MAX is set up and if it does
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// not have a valid fds number notify the user
val := os.Getenv("LOTUS_FD_MAX")
if val == "" {
val = os.Getenv("IPFS_FD_MAX")
}
if val != "" {
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fds, err := strconv.ParseUint(val, 10, 64)
if err != nil {
log.Errorf("bad value for LOTUS_FD_MAX: %s", err)
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return 0
}
return fds
}
return 0
}
// ManageFdLimit raise the current max file descriptor count
// of the process based on the LOTUS_FD_MAX value
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func ManageFdLimit() (changed bool, newLimit uint64, err error) {
if !supportsFDManagement {
return false, 0, nil
}
targetLimit := uint64(maxFds)
userLimit := userMaxFDs()
if userLimit > 0 {
targetLimit = userLimit
}
soft, hard, err := getLimit()
if err != nil {
return false, 0, err
}
if targetLimit <= soft {
return false, 0, nil
}
// the soft limit is the value that the kernel enforces for the
// corresponding resource
// the hard limit acts as a ceiling for the soft limit
// an unprivileged process may only set it's soft limit to a
// alue in the range from 0 up to the hard limit
err = setLimit(targetLimit, targetLimit)
switch err {
case nil:
newLimit = targetLimit
case syscall.EPERM:
// lower limit if necessary.
if targetLimit > hard {
targetLimit = hard
}
// the process does not have permission so we should only
// set the soft value
err = setLimit(targetLimit, hard)
if err != nil {
err = fmt.Errorf("error setting ulimit wihout hard limit: %s", err)
break
}
newLimit = targetLimit
// Warn on lowered limit.
if newLimit < userLimit {
err = fmt.Errorf(
"failed to raise ulimit to LOTUS_FD_MAX (%d): set to %d",
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userLimit,
newLimit,
)
break
}
if userLimit == 0 && newLimit < minFds {
err = fmt.Errorf(
"failed to raise ulimit to minimum %d: set to %d",
minFds,
newLimit,
)
break
}
default:
err = fmt.Errorf("error setting: ulimit: %s", err)
}
return newLimit > 0, newLimit, err
}