[PATCH] erofs-utils: lib: name worker threads erofs_compress

[PATCH] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like \`top\`, \`htop\`, or \`ps\`.

This utilizes \`prctl(PR_SET_NAME)\` on Linux and \`pthread_setname_np\`
on macOS to explicitly label these threads as \"erofs_compress\" upon
initialization.

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 lib/workqueue.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/workqueue.c b/lib/workqueue.c
index 18ee0f9..860e403 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -2,6 +2,9 @@
 #include <pthread.h>
 #include <stdlib.h>
 #include "erofs/workqueue.h"
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
 
 static void *worker_thread(void *arg)
 {
@@ -9,6 +12,12 @@ static void *worker_thread(void *arg)
 	struct erofs_work *work;
 	void *tlsp = NULL;
 
+#if defined(__linux__)
+	prctl(PR_SET_NAME, "erofs_compress");
+#elif defined(__APPLE__)
+	pthread_setname_np("erofs_compress");
+#endif
+
 	if (wq->on_start)
 		tlsp = (wq->on_start)(wq, NULL);
 
-- 
2.51.0

Re: [PATCH] erofs-utils: lib: name worker threads erofs_compress

[Gao Xiang]

On 2026/3/16 23:13, Nithurshen wrote:
> Set a specific thread name for the multi-threaded workqueue workers
> to make debugging, profiling, and process monitoring significantly
> easier.
> 
> Previously, worker threads inherited the name of the parent process
> (e.g., mkfs.erofs), making it difficult to distinguish them from the
> main thread in tools like \`top\`, \`htop\`, or \`ps\`.

Please just use `top`, `htop`, or `ps` here.

> 
> This utilizes \`prctl(PR_SET_NAME)\` on Linux and \`pthread_setname_np\`
> on macOS to explicitly label these threads as \"erofs_compress\" upon
> initialization.

Why not just calling erofs_compressor, since those worker are really
compressor.

> 
> Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
> ---
>   lib/workqueue.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/lib/workqueue.c b/lib/workqueue.c
> index 18ee0f9..860e403 100644
> --- a/lib/workqueue.c
> +++ b/lib/workqueue.c
> @@ -2,6 +2,9 @@
>   #include <pthread.h>
>   #include <stdlib.h>
>   #include "erofs/workqueue.h"
> +#if defined(__linux__)
> +#include <sys/prctl.h>
> +#endif
>   
>   static void *worker_thread(void *arg)
>   {
> @@ -9,6 +12,12 @@ static void *worker_thread(void *arg)
>   	struct erofs_work *work;
>   	void *tlsp = NULL;
>   
> +#if defined(__linux__)
> +	prctl(PR_SET_NAME, "erofs_compress");
> +#elif defined(__APPLE__)
> +	pthread_setname_np("erofs_compress");
> +#endif

I don't think they should be added here, you could
add in .on_start() of lib/compress.c instead.

Thanks,
Gao Xiang

> +
>   	if (wq->on_start)
>   		tlsp = (wq->on_start)(wq, NULL);
>   

[PATCH v2] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like `top`, `htop`, or `ps`.

This utilizes `prctl(PR_SET_NAME)` on Linux and `pthread_setname_np`
on macOS to explicitly label these threads as "erofs_compress" upon
initialization.

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 lib/workqueue.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/workqueue.c b/lib/workqueue.c
index 18ee0f9..860e403 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -2,6 +2,9 @@
 #include <pthread.h>
 #include <stdlib.h>
 #include "erofs/workqueue.h"
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
 
 static void *worker_thread(void *arg)
 {
@@ -9,6 +12,12 @@ static void *worker_thread(void *arg)
 	struct erofs_work *work;
 	void *tlsp = NULL;
 
+#if defined(__linux__)
+	prctl(PR_SET_NAME, "erofs_compress");
+#elif defined(__APPLE__)
+	pthread_setname_np("erofs_compress");
+#endif
+
 	if (wq->on_start)
 		tlsp = (wq->on_start)(wq, NULL);
 
-- 
2.51.0

Re: [PATCH v2] erofs-utils: lib: name worker threads erofs_compress

[Gao Xiang]

On 2026/3/17 00:54, Nithurshen wrote:

..

>   static void *worker_thread(void *arg)
>   {
> @@ -9,6 +12,12 @@ static void *worker_thread(void *arg)
>   	struct erofs_work *work;
>   	void *tlsp = NULL;
>   
> +#if defined(__linux__)
> +	prctl(PR_SET_NAME, "erofs_compress");
> +#elif defined(__APPLE__)
> +	pthread_setname_np("erofs_compress");
> +#endif

I'm not happy with this part, please read the v1 reply.

[PATCH v3] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like top, htop, or ps.

This utilizes prctl(PR_SET_NAME) on Linux and pthread_setname_np
on macOS to explicitly label these threads as "erofs_compressor" upon
initialization in the workqueue's .on_start() callback.

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 lib/compress.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/compress.c b/lib/compress.c
index 4a0d890..66b3b8b 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -26,6 +26,9 @@
 #include "liberofs_compress.h"
 #include "liberofs_fragments.h"
 #include "liberofs_metabox.h"
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
 
 #define Z_EROFS_DESTBUF_SZ	(Z_EROFS_PCLUSTER_MAX_SIZE + EROFS_MAX_BLOCK_SIZE * 2)
 
@@ -1427,6 +1430,12 @@ void *z_erofs_mt_wq_tls_alloc(struct erofs_workqueue *wq, void *ptr)
 {
 	struct erofs_compress_wq_tls *tls;
 
+#if defined(__linux__)
+	prctl(PR_SET_NAME, "erofs_compress");
+#elif defined(__APPLE__)
+	pthread_setname_np("erofs_compress");
+#endif
+
 	tls = calloc(1, sizeof(*tls));
 	if (!tls)
 		return NULL;
-- 
2.51.0

Re: [PATCH v3] erofs-utils: lib: name worker threads erofs_compress

[Gao Xiang]

On 2026/3/17 01:02, Nithurshen wrote:

..


> @@ -1427,6 +1430,12 @@ void *z_erofs_mt_wq_tls_alloc(struct erofs_workqueue *wq, void *ptr)
>   {
>   	struct erofs_compress_wq_tls *tls;
>   
> +#if defined(__linux__)
> +	prctl(PR_SET_NAME, "erofs_compress");
> +#elif defined(__APPLE__)
> +	pthread_setname_np("erofs_compress");
> +#endif

Why not call them as `erofs_compressor`?

and could we wrap it up as a new function like:

erofs_set_thread_name() somewhere instead so that
users can use it easier instead?

Thanks,
Gao Xiang

> +
>   	tls = calloc(1, sizeof(*tls));
>   	if (!tls)
>   		return NULL;

Re: [PATCH] erofs-utils: lib: name worker threads erofs_compress

[Nithurshen Karthikeyan]

Hi Xiang,

Sorry for the confusion. I sent the v2 patch before reading your
v1 reply, as I noticed the quotes formatting was off in my first
submission and wanted to fix it.

On Mon, Mar 16, 2026 at 10:19 PM Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>
> On 2026/3/16 23:13, Nithurshen wrote:
> > Set a specific thread name for the multi-threaded workqueue workers
> > to make debugging, profiling, and process monitoring significantly
> > easier.
> >
> > Previously, worker threads inherited the name of the parent process
> > (e.g., mkfs.erofs), making it difficult to distinguish them from the
> > main thread in tools like \`top\`, \`htop\`, or \`ps\`.
>
> Please just use `top`, `htop`, or `ps` here.

Yes, I have taken care of this in the updated commit message.

> > This utilizes \`prctl(PR_SET_NAME)\` on Linux and \`pthread_setname_np\`
> > on macOS to explicitly label these threads as \"erofs_compress\" upon
> > initialization.
>
> Why not just calling erofs_compressor, since those worker are really
> compressor.

I initially tested using "erofs_compressor", but the OS thread naming
API (`prctl` with `PR_SET_NAME`) has a strict 16-byte limit,
which includes the null terminator.

Because "erofs_compressor" is exactly 16 characters long, the null
byte pushes it to 17 bytes. As a result, the kernel truncates it, and
it actually shows up as "erofs_compresso" in `ps` and `top`.

To keep the output looking clean and intentional, I chose to use
"erofs_compress" (14 chars) instead. Please let me know if you are
okay with this, or if you'd prefer a different abbreviation.

> > +#if defined(__linux__)
> > +     prctl(PR_SET_NAME, "erofs_compress");
> > +#elif defined(__APPLE__)
> > +     pthread_setname_np("erofs_compress");
> > +#endif
>
> I don't think they should be added here, you could
> add in .on_start() of lib/compress.c instead.

Yes, it has been moved to lib/compress.c

Thanks,
Nithurshen

Re: [PATCH] erofs-utils: lib: name worker threads erofs_compress

[Gao Xiang]

Hi Nithurshen,

On 2026/3/17 01:11, Nithurshen Karthikeyan wrote:
> Hi Xiang,
> 

...

>>
>> Why not just calling erofs_compressor, since those worker are really
>> compressor.
> 
> I initially tested using "erofs_compressor", but the OS thread naming
> API (`prctl` with `PR_SET_NAME`) has a strict 16-byte limit,
> which includes the null terminator.
> 
> Because "erofs_compressor" is exactly 16 characters long, the null
> byte pushes it to 17 bytes. As a result, the kernel truncates it, and
> it actually shows up as "erofs_compresso" in `ps` and `top`.
> 
> To keep the output looking clean and intentional, I chose to use
> "erofs_compress" (14 chars) instead. Please let me know if you are
> okay with this, or if you'd prefer a different abbreviation.

Ok, or just call it as `erofscompressor`?
`erofs_compress` is really awkward to me.

Thanks,
Gao Xiang

[PATCH v4] erofs-utils: lib: name worker threads erofscompressor

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like top, htop, or ps.

This introduces a new OS-independent wrapper, erofs_set_thread_name(),
which utilizes prctl(PR_SET_NAME) on Linux and pthread_setname_np on
macOS. This helper is now called during the workqueue's .on_start()
callback in compress.c to explicitly label the worker threads as
"erofscompressor".

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 include/erofs/workqueue.h |  2 ++
 lib/compress.c            |  2 ++
 lib/workqueue.c           | 13 +++++++++++++
 3 files changed, 17 insertions(+)

diff --git a/include/erofs/workqueue.h b/include/erofs/workqueue.h
index 36037c3..27d3ba4 100644
--- a/include/erofs/workqueue.h
+++ b/include/erofs/workqueue.h
@@ -31,4 +31,6 @@ int erofs_alloc_workqueue(struct erofs_workqueue *wq, unsigned int nworker,
 			  erofs_wq_func_t on_exit);
 int erofs_queue_work(struct erofs_workqueue *wq, struct erofs_work *work);
 int erofs_destroy_workqueue(struct erofs_workqueue *wq);
+
+void erofs_set_thread_name(const char *name);
 #endif
diff --git a/lib/compress.c b/lib/compress.c
index 4a0d890..65971c9 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -1427,6 +1427,8 @@ void *z_erofs_mt_wq_tls_alloc(struct erofs_workqueue *wq, void *ptr)
 {
 	struct erofs_compress_wq_tls *tls;
 
+	erofs_set_thread_name("erofscompressor");
+
 	tls = calloc(1, sizeof(*tls));
 	if (!tls)
 		return NULL;
diff --git a/lib/workqueue.c b/lib/workqueue.c
index 18ee0f9..c924c1b 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -3,6 +3,19 @@
 #include <stdlib.h>
 #include "erofs/workqueue.h"
 
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
+
+void erofs_set_thread_name(const char *name)
+{
+	#if defined(__linux__)
+		prctl(PR_SET_NAME, name);
+	#elif defined(__APPLE__)
+		pthread_setname_np(name);
+	#endif
+}
+
 static void *worker_thread(void *arg)
 {
 	struct erofs_workqueue *wq = arg;
-- 
2.51.0

Re: [PATCH v4] erofs-utils: lib: name worker threads erofscompressor

[Gao Xiang]

On 2026/3/17 01:25, Nithurshen wrote:

..

> diff --git a/lib/workqueue.c b/lib/workqueue.c
> index 18ee0f9..c924c1b 100644
> --- a/lib/workqueue.c
> +++ b/lib/workqueue.c
> @@ -3,6 +3,19 @@
>   #include <stdlib.h>
>   #include "erofs/workqueue.h"
>   
> +#if defined(__linux__)
> +#include <sys/prctl.h>
> +#endif
> +
> +void erofs_set_thread_name(const char *name)
> +{
> +	#if defined(__linux__)

nit: no indentation for all C macros.  Since you'd
like to contribute more, I hope you could read the
kernel code style too.

Thanks,
Gao Xiang

> +		prctl(PR_SET_NAME, name);
> +	#elif defined(__APPLE__)
> +		pthread_setname_np(name);
> +	#endif
> +}
> +
>   static void *worker_thread(void *arg)
>   {
>   	struct erofs_workqueue *wq = arg;

[PATCH v5] erofs-utils: lib: name worker threads erofscompressor

[Nithurshen]

Set a specific thread name for the multi-threaded workqueue workers
to make debugging, profiling, and process monitoring significantly
easier.

Previously, worker threads inherited the name of the parent process
(e.g., mkfs.erofs), making it difficult to distinguish them from the
main thread in tools like top, htop, or ps.

This introduces a new OS-independent wrapper, erofs_set_thread_name(),
which utilizes prctl(PR_SET_NAME) on Linux and pthread_setname_np on
macOS. This helper is now called during the workqueue's .on_start()
callback in compress.c to explicitly label the worker threads as
"erofscompressor".

Signed-off-by: Nithurshen <nithurshen.dev@gmail.com>
---
 include/erofs/workqueue.h |  2 ++
 lib/compress.c            |  2 ++
 lib/workqueue.c           | 13 +++++++++++++
 3 files changed, 17 insertions(+)

diff --git a/include/erofs/workqueue.h b/include/erofs/workqueue.h
index 36037c3..27d3ba4 100644
--- a/include/erofs/workqueue.h
+++ b/include/erofs/workqueue.h
@@ -31,4 +31,6 @@ int erofs_alloc_workqueue(struct erofs_workqueue *wq, unsigned int nworker,
 			  erofs_wq_func_t on_exit);
 int erofs_queue_work(struct erofs_workqueue *wq, struct erofs_work *work);
 int erofs_destroy_workqueue(struct erofs_workqueue *wq);
+
+void erofs_set_thread_name(const char *name);
 #endif
diff --git a/lib/compress.c b/lib/compress.c
index 4a0d890..65971c9 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -1427,6 +1427,8 @@ void *z_erofs_mt_wq_tls_alloc(struct erofs_workqueue *wq, void *ptr)
 {
 	struct erofs_compress_wq_tls *tls;
 
+	erofs_set_thread_name("erofscompressor");
+
 	tls = calloc(1, sizeof(*tls));
 	if (!tls)
 		return NULL;
diff --git a/lib/workqueue.c b/lib/workqueue.c
index 18ee0f9..1811c9c 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -3,6 +3,19 @@
 #include <stdlib.h>
 #include "erofs/workqueue.h"
 
+#if defined(__linux__)
+#include <sys/prctl.h>
+#endif
+
+void erofs_set_thread_name(const char *name)
+{
+#if defined(__linux__)
+	prctl(PR_SET_NAME, name);
+#elif defined(__APPLE__)
+	pthread_setname_np(name);
+#endif
+}
+
 static void *worker_thread(void *arg)
 {
 	struct erofs_workqueue *wq = arg;
-- 
2.51.0