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e978cc2a80
This commit replaces the previous approach of running pytest inside GDB’s Python interpreter. Instead, tests are executed by driving a persistent GDB process externally using pexpect. - pexpect: Python library for controlling interactive programs (used here to send commands to GDB and capture its output) - persistent GDB: keep one GDB session alive across multiple tests instead of starting a new process for each test Tests can now be executed via `./test.py gdb` or with `pytest test/scylla_gdb`. This improves performance and makes failures easier to debug since pytest no longer runs hidden inside GDB subprocesses. Closes scylladb/scylladb#24804
81 lines
3.1 KiB
Python
81 lines
3.1 KiB
Python
# Copyright 2025-present ScyllaDB
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#
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# SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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"""
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GDB helper functions for `scylla_gdb` tests.
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They should be loaded to GDB by "-x {dir}/gdb_utils.py}",
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when loaded, they can be run in gdb e.g. `python get_sstables()`
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Depends on helper functions injected to GDB by `scylla-gdb.py` script.
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(sharded, for_each_table, seastar_lw_shared_ptr, find_sstables, find_vptrs, resolve,
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get_seastar_memory_start_and_size).
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"""
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import gdb
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import uuid
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def get_schema():
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"""Execute GDB commands to get schema information."""
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db = sharded(gdb.parse_and_eval('::debug::the_database')).local()
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table = next(for_each_table(db))
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ptr = seastar_lw_shared_ptr(table['_schema']).get()
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print('schema=', ptr)
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def get_sstables():
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"""Execute GDB commands to get sstables information."""
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sst = next(find_sstables())
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print(f"sst=(sstables::sstable *)", sst)
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def get_task():
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"""
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Some commands need a task to work on. The following fixture finds one.
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Because we stopped Scylla while it was idle, we don't expect to find
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any ready task with get_local_tasks(), but we can find one with a
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find_vptrs() loop. I noticed that a nice one (with multiple tasks chained
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to it for "scylla fiber") is one from http_server::do_accept_one.
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"""
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for obj_addr, vtable_addr in find_vptrs():
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name = resolve(vtable_addr, startswith='vtable for seastar::continuation')
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if name and 'do_accept_one' in name:
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print(f"task={obj_addr.cast(gdb.lookup_type('uintptr_t'))}")
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break
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def get_coroutine():
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"""Similar to get_task(), but looks for a coroutine frame."""
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target = 'service::topology_coordinator::run() [clone .resume]'
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for obj_addr, vtable_addr in find_vptrs():
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name = resolve(vtable_addr)
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if name and name.strip() == target:
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print(f"coroutine_config={obj_addr.cast(gdb.lookup_type('uintptr_t'))}")
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def coroutine_debug_config(tmpdir):
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"""
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Check if scylla_find agrees with find_vptrs, for debugging.
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Execute GDB commands for coroutine debugging with detailed output.
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This test fails sometimes, but rarely and unreliably.
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We want to get a coredump from it the next time it fails.
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Sending a SIGSEGV should induce that.
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https://github.com/scylladb/scylladb/issues/22501
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"""
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target = 'service::topology_coordinator::run() [clone .resume]'
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target_addr = int(gdb.parse_and_eval(f"&'{target}'"))
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find_command = f"scylla find -a 0x{target_addr:x}"
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gdb.write(f"Didn't find {target} (0x{target_addr:x}). Running '{find_command}'\n")
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mem_range = get_seastar_memory_start_and_size()
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gdb.execute(find_command)
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gdb.write(f"Memory range: 0x{mem_range[0]:x} 0x{mem_range[1]:x}\n")
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gdb.write("Found coroutines:\n")
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for obj_addr, vtable_addr in find_vptrs():
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name = resolve(vtable_addr)
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if name and '.resume' in name.strip():
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gdb.write(f"{name}\n")
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core_filename = f"{tmpdir}/../scylla_gdb_coro_task-{uuid.uuid4()}.core"
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gdb.execute(f"gcore {core_filename}")
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raise gdb.error(f"No coroutine frames found with expected name. Dumped Scylla core to {core_filename}")
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