diff --git a/deploy b/deploy
old mode 100755
new mode 100644
diff --git a/deploy.nu b/deploy.nu
new file mode 100644
index 0000000..57bd666
--- /dev/null
+++ b/deploy.nu
@@ -0,0 +1,25 @@
+#!/usr/bin/env nu
+
+let version = (open pyproject.toml).project.version
+let zipfile = $"scgenerator-($version).zip"
+let help_page = "scgenerator.html"
+
+let filelist = (
+    git ls-files |
+    lines |
+    where {not ($in | str ends-with ".afphoto")} |
+    where {$in != "deploy.nu"}
+)
+
+^zip $zipfile ...$filelist
+
+open README.md |
+    str replace -a __VERSION__ $version |
+    pandoc --standalone --toc --template build/template.html |
+    save -f $'build/($help_page)'
+
+scp -O $zipfile $"fibnas:/volume1/web/($zipfile)"
+scp -O $zipfile $"fibnas:/volume1/web/scgenerator-latest.zip"
+scp -O $'build/($help_page)' $"fibnas:/volume1/web/($help_page)"
+
+rm $zipfile
diff --git a/examples/Optica_PM2000D/Optica_PM2000D.toml b/examples/Optica_PM2000D/Optica_PM2000D.toml
old mode 100755
new mode 100644
diff --git a/examples/Travers/Travers.toml b/examples/Travers/Travers.toml
old mode 100755
new mode 100644
diff --git a/examples/compute_coherence.py b/examples/compute_coherence.py
index 3eaef86..ad3d804 100644
--- a/examples/compute_coherence.py
+++ b/examples/compute_coherence.py
@@ -31,6 +31,22 @@ def propagate_all(n):
     return spec, props
 
 
+def quick_test():
+    t = sc.tspace(dt=1e-15, t_num=2048)
+    spec_0 = np.fft.fft(10e3 * np.exp(-((t / 70e-15) ** 2)))
+    spec = sc.Spectrum(
+        [np.exp(2j * np.pi * np.random.rand()) + spec_0 for _ in range(20)],
+        sc.wspace(t) + sc.units.nm_rads(800),
+        t,
+    )
+    _, (top, bot) = plt.subplots(2, 1, constrained_layout=True, height_ratios=[1, 5], sharex=True)
+    bot.plot(spec.wl_disp * 1e9, spec[0].wl_int)
+    top.plot(spec.wl_disp * 1e9, spec.coherence())
+    top.set_xlim(750, 850)
+    bot.set_yscale("log")
+    plt.show()
+
+
 def main():
     n = 1
     spec, props = propagate_all(n)
@@ -52,4 +68,5 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    quick_test()
+    # main()
diff --git a/examples/show_multi_bar.py b/examples/show_multi_bar.py
new file mode 100644
index 0000000..4ed2d91
--- /dev/null
+++ b/examples/show_multi_bar.py
@@ -0,0 +1,22 @@
+import random
+import time
+
+import scgenerator as sc
+
+SIZE = 100
+
+
+def compute_stuff(num: int, pbar: sc.threading.Multibar):
+    speed = random.random() * 5
+    for i in pbar(range(SIZE), desc=f"num {num}"):
+        time.sleep(0.05 * speed * random.random())
+        if random.random() > 0.98:
+            print(f"some text {i}")
+
+
+def main():
+    sc.threading.apply_with_progress(compute_stuff, range(12), n_cpu=4, unpack=False)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/pyproject.toml b/pyproject.toml
index f860e8a..8a100b7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "scgenerator"
-version = "0.4.1"
+version = "0.4.2"
 description = "Simulate nonlinear pulse propagation in optical fibers"
 readme = "README.md"
 authors = [{ name = "Benoit Sierro", email = "benoit.sierro@iap.unibe.ch" }]
diff --git a/src/scgenerator/__init__.py b/src/scgenerator/__init__.py
index 7eac434..abe2950 100644
--- a/src/scgenerator/__init__.py
+++ b/src/scgenerator/__init__.py
@@ -1,5 +1,5 @@
 # ruff: noqa
-from scgenerator import math
+from scgenerator import math, threading
 from scgenerator.physics import units
 from scgenerator import io, noise, operators, plotting
 from scgenerator.helpers import *
diff --git a/src/scgenerator/threading.py b/src/scgenerator/threading.py
index 16e049c..f6e295e 100644
--- a/src/scgenerator/threading.py
+++ b/src/scgenerator/threading.py
@@ -1,19 +1,336 @@
+from __future__ import annotations
+
+import multiprocessing
+from collections.abc import Iterable, Iterator
+from dataclasses import dataclass
+from enum import Enum, auto
 from multiprocessing import Queue
-from threading import Thread
+from threading import Lock, Thread
+from typing import NamedTuple, TypeVar, Callable, Any
 
 from tqdm import tqdm
 
+import sys
 
-class Multibar(Thread):
+T = TypeVar("T")
+
+
+class Command(Enum):
+    INCREASE = auto()
+    NEW_TOTAL = auto()
+    FINISHED = auto()
+    STOP_ALL = auto()
+    NEW_NAME = auto()
+    PRINT = auto()
+
+
+class PBarMessage(NamedTuple):
+    bar_id: int
+    command: Command
+    data: int | float | str = 0
+
+
+class QueueStdOut:
+    id: int
     queue: Queue
-    bars: list[tqdm]
 
-    def __init__(self, bars: list[tqdm], queue: Queue):
+    def __init__(self, id: int, queue: Queue):
+        self.id = id
         self.queue = queue
-        self.bars = bars
+
+    def write(self, s: str):
+        self.queue.put(PBarMessage(self.id, Command.PRINT, s))
+
+
+class DelayedTqdm:
+    current: int | float
+    total: int | float | None
+    position_getter: PositionGetter
+    position: int | None
+    bar: tqdm | None
+    label: str | None
+
+    def __init__(self, position_getter: PositionGetter, total: int | float | None = None):
+        self.current = 0
+        self.total = total
+        self.position_getter = position_getter
+        self.position = None
+        self.bar = None
+        self.label = None
+
+    @property
+    def finished(self) -> bool:
+        return self.bar is not None and self.bar.disable
+
+    def show(self):
+        if self.bar is not None:
+            return
+        self.position = self.position_getter.book()
+        if self.position is None:
+            return
+        self.bar = tqdm(
+            total=self.total,
+            position=self.position,
+            desc=self.label,
+            initial=self.current,
+            leave=False,
+        )
+
+    def close(self):
+        if self.bar is None or self.bar.disable:
+            return
+        self.bar.close()
+        self.position_getter.free(self.position)
+
+    def update(self, amount: int | float = 1):
+        self.show()
+        self.current += amount
+        if self.bar is not None:
+            self.bar.update(amount)
+
+    def new_total(self, total: int | float):
+        self.show()
+        self.total = total
+        if self.bar is not None:
+            self.bar.total = total
+
+    def new_name(self, name: str):
+        self.show()
+        self.label = name
+        if self.bar is not None:
+            self.bar.set_description(self.label)
+
+
+class PositionGetter:
+    def __init__(self, n_tot: int, n: int, offset: int = 0):
+        self.remaining = n_tot
+        self.offset = offset
+        self.busy_at = [False for _ in range(n_tot)]
+
+    @property
+    def max_pos(self) -> int:
+        return max(self.busy_at)
+
+    def book(self) -> int:
+        for pos, busy in enumerate(self.busy_at[: self.remaining]):
+            if not busy:
+                self.busy_at[pos] = True
+                self.remaining -= 1
+                return pos + self.offset
+
+    def free(self, pos: int):
+        self.busy_at[pos - self.offset] = False
+
+
+class MultibarThread(Thread):
+    queue: Queue
+    main_pbar: tqdm
+    sub_pbars: list[DelayedTqdm]
+
+    def __init__(
+        self, n_bars: int, n_show: int, queue: Queue, default_total: int | float | None = None
+    ):
+        super().__init__()
+        self.queue = queue
+
+        pos_getter = PositionGetter(n_bars, n_show, offset=1)
+
+        self.sub_pbars = [DelayedTqdm(pos_getter, total=default_total) for _ in range(n_bars)]
+        self.main_pbar = tqdm(
+            total=sum((bar.total or 0) for bar in self.sub_pbars), position=0, colour="green"
+        )
+        self.started = False
+        self.finished = False
+        self.lock = Lock()
+
+    def __enter__(self):
+        self.start()
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        try:
+            self.close()
+        except AttributeError:
+            # maybe eager thread cleanup upon external error
+            if (exc_type, exc_value, traceback) == (None, None, None):
+                raise
+
+    def start(self):
+        if not self.started:
+            self.started = True
+            super().start()
+        return self
 
     def run(self):
         while True:
-            bar_id, amount = self.queue.get(True, None)
-            self.bars[bar_id].update(amount)
-            self.bars[0].update(amount)
+            msg = self._get_next()
+            if msg.command is Command.INCREASE:
+                self.sub_pbars[msg.bar_id].update(msg.data)
+                self.main_pbar.update(msg.data)
+            elif msg.command is Command.NEW_TOTAL:
+                pbar = self.sub_pbars[msg.bar_id].new_total(msg.data)
+                self.main_pbar.total = sum((bar.total or 0) for bar in self.sub_pbars)
+            elif msg.command is Command.NEW_NAME:
+                self.sub_pbars[msg.bar_id].new_name(msg.data)
+            elif msg.command is Command.PRINT:
+                self.main_pbar.write(f"{msg.bar_id}: {msg.data}")
+                self.main_pbar.refresh()
+            elif msg.command is Command.FINISHED:
+                pbar = self.sub_pbars[msg.bar_id]
+                pbar.close()
+                if all(bar.finished for bar in self.sub_pbars):
+                    self.main_pbar.close()
+            elif msg.command is Command.STOP_ALL:
+                self.close_all()
+                with self.lock:
+                    self.finished = True
+                return
+
+    def _get_next(self) -> PBarMessage:
+        return self.queue.get(True, None)
+
+    def close_all(self):
+        for bar in self.sub_pbars:
+            bar.close()
+        self.main_pbar.close()
+
+    def close(self):
+        with self.lock:
+            if not self.finished:
+                self.queue.put(PBarMessage(0, Command.STOP_ALL))
+        self.join()
+
+
+class Multibar:
+    """lives in a subprocess"""
+
+    id: int
+    total: float | int
+    current: float | int
+    queue: Queue | None = None
+
+    def __init__(
+        self, id: int, queue: Queue, total: int | float | None = None, start: int | float = 0
+    ):
+        self.id = id
+        self.total = total
+        self.current = start
+        self.queue = queue
+        self.finished = False
+        self.stdout = QueueStdOut(self.id, self.queue)
+
+        sys.stdout = self.stdout
+        sys.stderr = self.stdout
+
+        print(sys.stdout, file=sys.__stdout__)
+
+    def update(self, amount: float | int = 1):
+        self.check_start_finish()
+        self.current += amount
+        self.queue.put(PBarMessage(self.id, Command.INCREASE, amount))
+        if self.total is not None and self.current >= self.total:
+            self.queue.put(PBarMessage(self.id, Command.FINISHED))
+            self.finished = True
+
+    def close(self):
+        self.queue.put(PBarMessage(self.id, Command.FINISHED))
+        sys.stdout = sys.__stdout__
+        sys.stderr = sys.__stderr__
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
+    def __call__(
+        self, iterable: Iterable[T], total: int | float | None = None, desc: str | None = None
+    ) -> Iterator[T]:
+        self.check_start_finish()
+        try:
+            new_len = len(iterable)
+        except TypeError:
+            if total is None:
+                raise
+            new_len = total
+
+        if desc is not None:
+            self.queue.put(PBarMessage(self.id, Command.NEW_NAME, desc))
+        self.queue.put(PBarMessage(self.id, Command.NEW_TOTAL, new_len))
+        self.total = total
+
+        iterable = iter(iterable)
+        while True:
+            try:
+                yield next(iterable)
+            except StopIteration:
+                break
+            except Exception:
+                self.queue.put(PBarMessage(self.id, Command.FINISHED))
+                self.finished = True
+                raise
+            self.update()
+        self.queue.put(PBarMessage(self.id, Command.FINISHED))
+        self.finished = True
+
+    def check_start_finish(self):
+        if self.finished:
+            raise ValueError(f"{self.__class__.__name__} {self.id} has already finished")
+
+
+@dataclass
+class MultibarManager:
+    thread: MultibarThread
+    queue: Queue
+    mbars: list[Multibar]
+
+    def __enter__(self):
+        self.thread.start()
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        try:
+            self.thread.close()
+            # self.queue.close()
+            # self.queue.join_thread()
+        except AttributeError:
+            # maybe eager thread cleanup upon external error
+            if (exc_type, exc_value, traceback) == (None, None, None):
+                raise
+
+    def __getitem__(self, key: int) -> Multibar:
+        if not self.thread.is_alive():
+            raise RuntimeError("You must start the multibar thread before using the multibars")
+        return self.mbars[key]
+
+    def __iter__(self) -> Iterator[Multibar]:
+        yield from self.mbars
+
+
+def multibar(n_tasks: int, n_show: int, n_pertask: int | float | None = None) -> MultibarThread:
+    manager = multiprocessing.Manager()
+    queue = manager.Queue()
+    thread = MultibarThread(n_tasks, n_show, queue, n_pertask)
+
+    mbars = [Multibar(i, queue, n_pertask) for i in range(n_tasks)]
+    return MultibarManager(thread, queue, mbars)
+
+
+def apply_with_progress(
+    func: Callable[..., T],
+    args: Iterable[Iterable[Any]],
+    n_cpu: int | None = None,
+    n_pertask: int | None = None,
+    unpack: bool = True,
+) -> list[T]:
+    args = list(args)
+    n_cpu = n_cpu or multiprocessing.cpu_count()
+    with (
+        multiprocessing.Pool(n_cpu) as pool,
+        multibar(n_tasks=len(args), n_show=n_cpu, n_pertask=n_pertask) as bars,
+    ):
+        if unpack:
+            all_args = ((*arg, bars[i]) for i, arg in enumerate(args))
+        else:
+            all_args = ((arg, bars[i]) for i, arg in enumerate(args))
+        return pool.starmap(func, all_args)