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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 yet? Point Loadbars at a handful of hosts and see who's busy 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.

• 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). Handy to tell whether a box is slow because of CPU or disk. With many hosts, the disk-heavy one 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. It catches short spikes that the stacked bar might smooth out.

• 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.

• 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. With hundreds of bars you see at once which hosts are above or below average.

• Global I/O average line (key i): same idea for iowait+IRQ, to spot the hosts waiting on I/O more than the rest.

• Host separator lines (key s): a thin red vertical line between each host's bars.

• Scale reset (key r): reset the auto-scale for load and disk back to the floor, e.g. after a big spike.

• Toggle CPU off (key 1 cycles through aggregate → per-core → off): the Perl version didn't let you turn CPU bars off.

• maxbarsperrow: wrap bars into multiple rows instead of one long row.

• 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. No need to press 2, 3, 4, 5 every time.

• Window title (--title): set the SDL window title. Handy to tell several Loadbars windows apart in your taskbar.

• SSH options (--sshopts): pass extra flags to ssh (e.g. ConnectTimeout, ProxyJump). That way you don't have to change your global SSH config for a one-off session.

• hasagent: skip extra SSH agent checks when you know the key is already loaded. Avoids startup delay or warnings when you've already run ssh-add.

• 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.

• 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. No Linux VM needed to watch production from a laptop.

• Single static binary: no Perl runtime, no SDL Perl modules, no CPAN. Copy one file to a jump host and run it.

• Unit tests: mage test (or go test). The Go version has proper tests.

• Window resize (arrow keys): resize the window with the keyboard (left/right = width, up/down = height). 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.

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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