---
name: pperl-specific diagnostics
---
# pperl-specific diagnostics

Messages PetaPerl emits that have no counterpart in upstream
Perl. Most concern the daemon mode - pperl's persistent-process
feature, which has no analogue in a stock perl - and a few native
modules with pperl-specific behavior.

## Daemon mode

`pperl` can run a script as a resident daemon and dispatch
requests to it, which avoids paying interpreter startup on every
call. The daemon diagnostics report problems with that channel.

### `` `Daemon already running for this script (socket: %s)` ``

**(F)**

A `--daemon` start was requested for a script that already has a
running daemon. The socket path is shown. Stop the existing daemon
first, or connect to it instead of starting a new one.

### `` `Cannot connect to daemon (%s): %s` ``

**(F)**

A client could not reach the daemon socket. The message continues
with one of two hints depending on context - `Start with: pperl
--daemon <script>` when no daemon appears to be running, or `Is
the daemon running?` when the socket exists but the connection
failed. Start the daemon, or check that the socket path matches.

## Native modules

### `` `ERRNO hash is read only!` ``

**(F)**

Code tried to assign to `%!` (the `Errno` symbolic-error hash)
or to one of its keys. That hash is populated by the runtime and
reflects the current `errno`; it is not writable. Read it (`$!{ENOENT}`)
rather than assigning to it.

### `` `Hash has key '%s' which is not in the new key set` ``

**(F)**

From `Hash::Util`: a `lock_keys` call supplied an explicit key set
that does not include a key the hash already contains. Locking
cannot proceed because that existing key would become inaccessible.
Either include the existing key in the new set, or delete it before
locking.

### `` `Time::HiRes::usleep(%s): negative time not invented yet` ``

**(F)**

A `Time::HiRes` sleep function was given a negative duration. Time
runs forward; pass a non-negative number of microseconds (or
nanoseconds for `nanosleep`). The `nanosleep` form reports the
same with its own name.

### `` `%s version %s required--this is only version %s` ``

**(F)**

A `use Module VERSION` (or an explicit version check) demanded a
newer version of a module than the one installed. The message
names the module, the version requested, and the version present.
Install or load the required version.

## See also

- [Internal errors](internal) - the panics that mean a pperl bug
  rather than a usage error.
- [Disclaimer & bug reports](../../../disclaimer) - how pperl
  diverges from stock perl, and where to report problems.
- [`Errno`](../../Errno) - the module behind `%!`, the read-only
  symbolic-errno hash.
- [`Hash::Util`](../../Hash/Util) - `lock_keys` and the
  restricted-hash machinery.