In the image obtained from running bitcoin-core’s interface_ipc_mining test below, there are two “b-capnp-loop” threads: only one (Thread ID 11) is the actual worker thread calling createNewBlock().
This creates confusion for the developer trying to find the right thread to inspect.
I took a quick stab at this and tried to set the name of the newly created thread in ProxyServer<ThreadMap>::makeThread, but it didn’t seem to work.
You can reproduce with this diff applied to bitcoin-core and using GDB to inspect the running threads.
0diff --git a/src/interfaces/mining.h b/src/interfaces/mining.h
1index f4c42e204a..bbef70196b 100644
2--- a/src/interfaces/mining.h
3+++ b/src/interfaces/mining.h
4@@ -139,6 +139,13 @@ public:
5 */
6 virtual void interrupt() = 0;
7
8+ /**
9+ * Sets the debug mining flag.
10+ *
11+ * [@param](/bitcoin-core-multiprocess/contributor/param/)[in] debug_mining whether to enable debug mining mode
12+ */
13+ virtual void setDebugMining(bool debug_mining) = 0;
14+
15 /**
16 * Checks if a given block is valid.
17 *
18diff --git a/src/ipc/capnp/mining.capnp b/src/ipc/capnp/mining.capnp
19index 64cad4d49f..38a1758f61 100644
20--- a/src/ipc/capnp/mining.capnp
21+++ b/src/ipc/capnp/mining.capnp
22@@ -25,6 +25,7 @@ interface Mining $Proxy.wrap("interfaces::Mining") {
23 createNewBlock [@4](/bitcoin-core-multiprocess/contributor/4/) (context :Proxy.Context, options: BlockCreateOptions, cooldown: Bool = true) -> (result: BlockTemplate);
24 checkBlock [@5](/bitcoin-core-multiprocess/contributor/5/) (context :Proxy.Context, block: Data, options: BlockCheckOptions) -> (reason: Text, debug: Text, result: Bool);
25 interrupt [@6](/bitcoin-core-multiprocess/contributor/6/) () -> ();
26+ setDebugMining [@7](/bitcoin-core-multiprocess/contributor/7/) (debugMining: Bool) -> ();
27 }
28
29 interface BlockTemplate $Proxy.wrap("interfaces::BlockTemplate") {
30diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
31index 84fd5bb794..e83e7ea003 100644
32--- a/src/node/interfaces.cpp
33+++ b/src/node/interfaces.cpp
34@@ -959,6 +959,9 @@ public:
35
36 std::unique_ptr<BlockTemplate> createNewBlock(const BlockCreateOptions& options, bool cooldown) override
37 {
38+ if (m_debug_mining) {
39+ while (true) {} //DEBUG
40+ }
41 // Reject too-small values instead of clamping so callers don't silently
42 // end up mining with different options than requested. This matches the
43 // behavior of the `-blockreservedweight` startup option, which rejects
44@@ -999,6 +1002,11 @@ public:
45 InterruptWait(notifications(), m_interrupt_mining);
46 }
47
48+ void setDebugMining(bool debug_mining) override
49+ {
50+ m_debug_mining = debug_mining;
51+ }
52+
53 bool checkBlock(const CBlock& block, const node::BlockCheckOptions& options, std::string& reason, std::string& debug) override
54 {
55 LOCK(chainman().GetMutex());
56@@ -1013,6 +1021,7 @@ public:
57 KernelNotifications& notifications() { return *Assert(m_node.notifications); }
58 // Treat as if guarded by notifications().m_tip_block_mutex
59 bool m_interrupt_mining{false};
60+ bool m_debug_mining{false};
61 NodeContext& m_node;
62 };
63 } // namespace
64diff --git a/test/functional/test_framework/ipc_util.py b/test/functional/test_framework/ipc_util.py
65index 11497463eb..1469294b63 100644
66--- a/test/functional/test_framework/ipc_util.py
67+++ b/test/functional/test_framework/ipc_util.py
68@@ -108,6 +108,8 @@ async def make_capnp_init_ctx(self):
69
70 async def mining_create_block_template(mining, stack, ctx, opts):
71 """Call mining.createNewBlock() and return template, then call template.destroy() when stack exits."""
72+ await mining.setDebugMining(True) # Block createNewBlock() infinitely
73+ import pdb; pdb.set_trace()
74 response = await mining.createNewBlock(ctx, opts)
75 if not response._has("result"):
76 return None
