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Loadbars 0.13.0 released

Table of Contents

• Loadbars 0.13.0 released
• ⇢ What Loadbars is (and isn't)
• ⇢ Use cases
• ⇢ What's new since the Perl version
• ⇢ Core features
• ⇢ ⇢ Load average bars
• ⇢ ⇢ Disk I/O bars
• ⇢ ⇢ Global reference lines and options
• ⇢ ⇢ CPU monitoring
• ⇢ ⇢ Memory and network
• ⇢ ⇢ All hotkeys
• ⇢ ⇢ SSH and config
• ⇢ ⇢ Building and platforms

What Loadbars is (and isn't)

┌─ Loadbars 0.13.0 ─────────────────────────────────────────┐
│                                                           │
│  ████  ████  ████  ██  ████  ████  ████  ██  ░░██  ░░██   │
│  ████  ████  ████  ██  ████  ████  ████  ██  ░░██  ░░██   │
│  ████  ████  ████  ██  ████  ████  ████  ██  ░░██  ░░██   │
│   CPU   cpu0  cpu1  mem  CPU   cpu0  cpu1  mem  net   net │
│  └──── host1 ────┘      └──── host2 ────┘                 │
└───────────────────────────────────────────────────────────┘

Use cases

• Deployments and rollouts: watch CPU, memory, and network across app servers or nodes while you deploy. Spot the one that isn't coming up or is stuck under load.
• Load testing: run your load tool against a cluster and see which hosts (or cores) are saturated, whether memory or disk I/O is the bottleneck, and how load spreads.
• Quick health sweep: no dashboards set up yet? SSH to a handful of hosts and run Loadbars. You get an instant picture of who's busy, who's idle, and who's swapping.
• Comparing hosts: side-by-side bars make it easy to see if one machine is hotter than the rest (e.g. after a config change or migration).
• Local tuning: run loadbars --hosts localhost while you benchmark or stress a single box; the bars and load-average view help correlate activity with what you're doing.

What's new since the Perl version

• Load average bars: the Perl version had no load average. Now you get 1/5/15-minute load per host. Useful because load average is the classic "how queued is this box" signal — you see saturation and trends at a glance without reading numbers.

• Disk I/O bars: disk was invisible in the Perl version. You now get read/write throughput (and optionally utilization %) per host or per device. Whole-disk devices only (partitions, loop, ram, zram, and device-mapper are excluded). Useful when you need to tell "is this slow because of CPU or because of disk?" — especially with many hosts, one disk-heavy host stands out. Disk smoothing (config diskaverage, hotkeys b/x) lets you tune how much the bars are averaged.

• Extended peak line on CPU: a 1px line shows max system+user over the last N samples. Useful to see short spikes that the stacked bar might smooth out, so you don't miss bursty load.

• Tooltips and host highlight: hover the mouse over any bar to see a tooltip with exact values (CPU %, memory, network, load, or disk depending on bar type). The hovered host's bars are highlighted (inverted) so you can tell which host you're over. Useful when you have hundreds of bars and want to read a specific number or confirm which host a bar belongs to.

• GuestNice in CPU bars: CPU bars now show GuestNice as a lime green segment (above Nice). One more breakdown for virtualized or container workloads.

• Version in window title: the default SDL title is "Loadbars <version> (press h for help on stdout)". Override with --title when you need a custom label.

• Global average CPU line (key g): a single red line across all hosts at the fleet-average CPU. Useful when you have hundreds of bars: you instantly see which hosts are above or below average without comparing bar heights in your head.

• Global I/O average line (key i): same idea for iowait+IRQ. Useful to spot which hosts are waiting on I/O more than the rest — quick way to find the disk-bound or interrupt-heavy machines.

• Host separator lines (key s): a thin red vertical line between each host's bars. Useful at scale so you don't lose track of where one host ends and the next begins when the window is full of bars.

• Scale reset (key r): reset the auto-scale for load and disk back to the floor. Useful after a big spike so the bars don't stay compressed for the rest of the session.

• Toggle CPU off (key 1 cycles through aggregate → per-core → off): the Perl version didn't let you turn CPU bars off. Useful when you want to focus only on memory, network, load, or disk and reduce clutter.

• maxbarsperrow: wrap bars into multiple rows instead of one long row. Useful with many hosts so the window doesn't become impossibly wide; you get a grid and can still scan everything.

• maxwidth: cap on window width in pixels (default 1900). Stops the window growing unbounded with many hosts; use together with maxbarsperrow for a predictable layout.

• Startup visibility flags: --showmem, --shownet, --showload, --extended, --cpumode, --diskmode (and friends) let you start with the bars you care about already on. Useful so you don't have to press 2, 3, 4, 5 every time.

• Window title (--title): set the SDL window title. Useful when you run several Loadbars windows (e.g. one per cluster or environment) and need to tell them apart in your taskbar or window list.

• SSH options (--sshopts): pass extra flags to ssh (e.g. ConnectTimeout, ProxyJump). Useful on locked-down or jump-host setups so Loadbars works without changing your global SSH config for a one-off session.

• hasagent: skip extra SSH agent checks when you know the key is already loaded. Useful to avoid startup delay or warnings when you've already run ssh-add and are monitoring many hosts.

• Config file covers every option: any flag from --help can be set in ~/.loadbarsrc (no leading --). Perl had a config but the Go version supports the full set. Useful for reproducible setups and sharing.

• Positional host arguments: you can run loadbars server1 server2 without --hosts. Convenience when you only have a few hosts.

• macOS as client: run the Loadbars binary on a Mac and connect to Linux servers via SSH. The Perl version was Linux-only. Useful to watch production from a laptop without a Linux VM or second machine.

• Single static binary: no Perl runtime, no SDL Perl modules, no CPAN. Useful for deployment — copy one file to a jump host or new machine and run it.

• Unit tests: mage test (or go test). The Go version has proper tests; useful for development and catching regressions.

• Window resize (arrow keys): resize the window with the keyboard (left/right = width, up/down = height). Useful to fit more or fewer bars on screen without touching the mouse. (The Perl version had mouse-based resize; Go uses arrow keys.)

• Hundreds of hosts in parallel: the Go implementation connects to all hosts concurrently and keeps polling without blocking. The Perl version struggled with many hosts. Useful for large fleets; you get a real "wall of bars" instead of a subset.

Core features

Load average bars

Disk I/O bars

Global reference lines and options

CPU monitoring

Memory and network

• 2 / m: memory — left half RAM (dark grey/black), right half Swap (grey/black) per host
• 3 / n: network — RX (top, light green) and TX (bottom) summed over non-loopback interfaces. Red bar = no non-lo interface. Use --netlink or f/v for link speed (utilization %). Default gbit.

All hotkeys

Key     Action
─────   ──────────────────────────────────────────────────
1       Toggle CPU (aggregate / per-core / off)
2 / m   Toggle memory bars
3 / n   Toggle network bars
4 / l   Toggle load average bars
5       Toggle disk I/O (aggregate / per-device / off)
r       Reset load and disk auto-scale peaks
e       Toggle extended (peak line on CPU; disk util line)
g       Toggle global average CPU line
i       Toggle global I/O average line
s       Toggle host separator lines
h       Print hotkey list to stdout
q       Quit
w       Write current settings to ~/.loadbarsrc
a / y   CPU average samples up / down
d / c   Net average samples up / down
b / x   Disk average samples up / down
f / v   Link scale up / down
Arrows  Resize window

SSH and config

loadbars --hosts server1,server2,server3
loadbars --hosts root@server1,root@server2
loadbars servername{01..50}.example.com --showcores 1
loadbars --cluster production

Building and platforms

mage build
./loadbars --hosts localhost
mage install   # to ~/go/bin
mage test

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