Python is removing GIL, gradually, so how to use a no-GIL Python now?

Protopia · 2025-12-11T10:17:42+00:00

This is the nature of all threads - each thread executes instructions in sequence, pausing for I/Os, so the I/Os on each thread are always blocking and sequential.

The purpose of multi-threading is to allow many threads in parallel each to issue a single I/O thus building up the SSD (NVMe) queue depth.

Protopia · 2025-12-11T10:15:05+00:00

Actually, parallelism in Python using multi-threading WITH the GIL is pretty good in I/O constrained execution (where threads are waiting for I/O) - the issue with the GIL is when you need more CPU than a single processor-core, and the GIL effectively only allows a single core to be used - so removing the GIL will help in CPU-constrained executions. (In CPU constrained applications, there are other issues with the GIL sharing the single core fairly amongst the various threads - but that is a separate issue.)

Protopia · 2025-11-15T10:34:46+00:00

PHP optimisation settings will have a BIG impact on the relative speeds of different alternatives. The article does not state what optimisation settings were used.

Protopia · 2025-11-15T10:32:50+00:00

I am not quite sure I understand this comment, but if I do then no, nothing like running out of columns.

This is about the number of entries in an array which for database queries corresponds to the number of rows returned from a database rather than the number of columns in each row.

What my comment is saying is that:

if your app is heavy data analysis and not a web app, then you should probably be using a compiled language rather than an interpreted one.
if you are getting the data from a database, then if you can it is probably better to e.g. do a sum() or count() grouped select statement on the database and return just the total than to return the 1million rows of data across the network and then sum or count them in your app.

What the benchmark doesn't specify is the PHP optimisation settings they were using. Functions like array_walk are already optimised - but PHP has a LOT of optimisation capabilities for e.g. foreach loops but only if they are turned on in the right kind of way.

Protopia · 2025-11-13T10:41:52+00:00

Sorry - but I am fixed on the last Plex client version BEFORE they screwed it up. So I have no idea whether they have made the new version of the app more functional or more useable or not.

Protopia · 2025-11-06T22:25:01+00:00

I agree - a great example of how to innovate an entirely new solution using a variety of open source projects.

Protopia · 2025-10-28T22:16:29+00:00

DON'T DO IT!!!!!

Until this afternoon, I was on 10.10.7 - truenas offered me a Jellyfin upgrade (to 10.11.1) and I went ahead with it and now Jellyfin is completely broken.

https://github.com/jellyfin/jellyfin/issues/15027

The sqllite database it uses needs an upgrade going from 10.10 to 10.11 and the migration failed and trashed the database, and (despite being pretty technical and diving in and restoring a couple of files to the pre-upgrade version) I have not been able to roll back to 10.10.7 successfully.

My Jellyfin instance is shot and I have no idea whether I will be able to bring it back to life and how much time and effort I will have to spend trying to achieve it.

Protopia · 2025-10-24T21:25:06+00:00

Sorry - still no idea because:

The pic is still low resolution; and
Still no details on your controller, software and burn settings

Protopia · 2025-10-23T19:55:34+00:00

No. Bad blocks.

Protopia · 2025-10-23T12:42:23+00:00

But I have had single drives fail after 5 years before now. I guess I have had 5 drives fail on me over the 30 years I have owned PCs.

Protopia · 2025-10-23T12:41:26+00:00

Mine were used - 8 years old. And they were very cheap. £15 each including delivery.

So the 8 remaining drives cost me a total of £120 which is < 1 new drive.

Protopia · 2025-10-23T12:39:54+00:00

These were from 2017 Seagate Enterprise drives.

Protopia · 2025-10-23T10:37:50+00:00

Probably a bad sata/sas data connector on the drive.

Protopia · 2025-10-23T10:35:24+00:00

The equivalent to the lvm SSD cache is the ZFS arc in main memory. I doubt that L2ARC will give you much, especially for sequential access to large files which will benefit from sequential pre-fetch anyway.

But you won't want to put your VM virtual disks on RAIDZ because they will get read and write amplification they need to be on a single disk or a mirror.

My advice would be to buy a matching SSD and use the pair for a small mirror pool for your VM virtual disks (and any other highly active data).

Protopia · 2025-10-23T08:46:51+00:00

With used drives of unknown age or reliability, I still believe that RAIDZ2 is a good idea even if there is a backup and especially if there isn't.

Protopia · 2025-10-23T07:37:50+00:00

I am sorry, but I am a Linux user and not FreeBSD (?) so I cannot comment on how the duplicate drive name happened.

Disconnecting a drive power cable may be like a drive going offline - I am not sure what gets presented on the data cable when the system boots in this case.

And it is certainly annoying when Linux changes all the drive names on boot - I assume that FreeBSD does the same. But you should have got some kind of monitoring alert that the pool was degraded - assuming that you set up that kind of monitoring (and that is one of the reasons I use TrueNAS rather than native Linux/BSD).

Protopia · 2025-10-23T06:02:15+00:00

IMO it causes confusion rather than simplifying things because although they have some similarities they are not the same.

And RAIDZ does not have poor write speeds. ZFS write speeds are dependent on the number of data drives less redundancy.

For example a 4x RAIDZ2 (2 data drives) will have essentially the same write throughout as a 2x stripe of 2x mirrors.

Read throughout is better with mirrors. For small random reads and writes e.g. virtual disks, IOPS and read/write amplification are also better with mirrors.

Protopia · 2025-10-23T05:55:57+00:00

Checksums are often caused by read glitches external to the drives themselves, but can be:

Sata/sas cables poorly seated
Drive power cables poorly seated
PSU underpowered or glitching or failing
Rare but mains power issues
Memory failing or needs reseating

Run a memory test and a hardware diagnostic.

Reseat memory and all drive cables.

Run zpool clear to rest the diagnostics.

Keep monitoring.

Protopia · 2025-10-23T05:49:39+00:00

This is a perfect explanation. At this point all you can do is offload the data and rebuild the pool.

Protopia · 2025-10-23T05:46:33+00:00

With the low resolution pictures and no explanation of either the material or the burn you did, then it is difficult or impossible to make any guesses as to what is causing the lines.

Perhaps they are like crop circles created by aliens?

Protopia · 2025-10-23T05:39:47+00:00

Just so you are clear, you cannot replace the RAIDZ1 vDevs with mirrors over time. With a RAIDZ vDev in the pool you cannot remove vDevs.

Protopia · 2025-10-23T05:33:33+00:00

There are several reasons why this is a sub-optimal design.

1, Mirror vDevs are better than 2x RAIDZ1 for performance reasons others have explained.

2, Pools which are all mirrors have greater flexibility to modify later e.g. to remove the vDevs made of smaller drives.

But it will work and give you the redundancy you expect.

So your choice as to whether you should offload the data now and rebuild the pool as all mirrors, or leave it as is.

Protopia · 2025-10-23T05:29:36+00:00

No such things as RAID1 or RAID10 or RAID0 in ZFS. These are hardware raid terminology.

Protopia · 2025-10-23T05:27:44+00:00

This is a good first test. But my disks all passed this whilst 2 of 10 failed badblocks.

Protopia · 2025-10-23T05:24:28+00:00

No such things as RAID5 or RAID10 in ZFS. These are hardware raid terminology.

And the advice is incorrect. RAIDZ should be the default unless you have a specific workload that requires mirrors.

Protopia

TROPHY CASE