Re: [tarantool-patches] [PATCH v2] xlog: add request details to panic message for broken LSN

[Sergei Kalashnikov <ztarvos@gmail.com>]

Hi Vladimir,

Thank you for review. Please find my answers inline.
I also included the fixed patch at the end of this mail.


On Mon, Aug 27, 2018 at 08:04:07PM +0300, Vladimir Davydov wrote:
> On Mon, Aug 27, 2018 at 02:22:24PM +0300, Sergei Kalashnikov wrote:
> > Aid the debugging of replication issues related to out-of-order
> > requests. Adds the details of request/tuple to the diagnostic
> > message whenever possible.
> > 
> > Closes #3105
> > ---
> > https://github.com/tarantool/tarantool/issues/3105
> > https://github.com/tarantool/tarantool/commits/ztarvos/gh-3105-log-request-broken-lsn
> 
> Please write a brief change log here, after the hyperlinks,
> when you re-submit a patch, e.g.
> 
> https://www.freelists.org/post/tarantool-patches/PATCH-v3-replication-do-not-ignore-replication-connect-quorum
> 
OK, got it!

> > diff --git a/src/box/relay.cc b/src/box/relay.cc
> > index 138e66d..2d0b651 100644
> > --- a/src/box/relay.cc
> > +++ b/src/box/relay.cc
> > @@ -678,4 +678,12 @@ relay_send_row(struct xstream *stream, struct xrow_header *packet)
> >  				      packet->replica_id)) {
> >  		relay_send(relay, packet);
> >  	}
> > +#ifndef NDEBUG
> 
> You don't really need 'ifndef NDEBUG' here. Please remove.
> 
Done.

> > +	struct errinj *inj = errinj(ERRINJ_RELAY_BREAK_LSN, ERRINJ_INT);
> > +	if (inj != NULL && packet->lsn == inj->iparam) {
> > +		relay_send(relay, packet);
> > +		diag_set(ClientError, ER_INJECTION,
> > +			 "relay broken lsn injection lsn");
> 
> There's no point in setting diag here. Please remove. At the same time,
> I think it would be useful if you logged the LSN of the row you mangled
> with say_warn() or say_error().
> 
Fixed. Added say_warn with the lsn.

> Also, IMO the code would be clearer if you modified LSN of the row
> before sending it instead of sending two rows.
> 
Done.

> > +	}
> > +#endif
> >  }
> > diff --git a/src/box/xlog.c b/src/box/xlog.c
> > index d399a72..46cf7ed 100644
> > --- a/src/box/xlog.c
> > +++ b/src/box/xlog.c
> > @@ -1246,6 +1246,14 @@ xlog_write_row(struct xlog *log, const struct xrow_header *packet)
> >  	size_t page_offset = obuf_size(&log->obuf);
> >  	/** encode row into iovec */
> >  	struct iovec iov[XROW_IOVMAX];
> > +#ifndef NDEBUG
> 
> Again, ifndef and diag aren't really needed here while logging would
> probably make sense.
> 
Fixed.

> > +	struct errinj *inj = errinj(ERRINJ_XLOG_BREAK_LSN, ERRINJ_INT);
> > +	if (inj != NULL && inj->iparam == packet->lsn) {
> > +		((struct xrow_header *)packet)->lsn = inj->iparam - 1;
> > +		diag_set(ClientError, ER_INJECTION,
> > +			 "xlog broken lsn injection lsn");
> > +	}
> > +#endif
> 
> I'd expect to see this error injection in wal.c - xlog_write_row() is
> used not only for writing xlogs, but also run and snap files, we don't
> want to mangle those.
> 
Moved to wal.c

> >  	/** don't write sync to the disk */
> >  	int iovcnt = xrow_header_encode(packet, 0, iov, 0);
> >  	if (iovcnt < 0) {
> > diff --git a/src/box/xrow.h b/src/box/xrow.h
> > index 4721670..f7eda91 100644
> > --- a/src/box/xrow.h
> > +++ b/src/box/xrow.h
> > @@ -522,6 +522,35 @@ xrow_to_iovec(const struct xrow_header *row, struct iovec *out);
> >  void
> >  xrow_decode_error(struct xrow_header *row);
> >  
> > +/**
> > + * Update vclock with the next LSN value for given replica id.
> > + * The function will cause panic if the next LSN happens to be
> > + * out of order. The details of provided row are included into
> > + * diagnostic message.
> > + *
> > + * @param vclock Vector clock.
> > + * @param row Data row.
> > + * @return Previous LSN value.
> > + */
> > +static inline int64_t
> > +vclock_follow_xrow(struct vclock* vclock, const struct xrow_header *row)
> > +{
> > +	assert(row);
> > +	assert(row->replica_id < VCLOCK_MAX);
> > +	if (row->lsn <= vclock->lsn[row->replica_id]) {
> > +		struct request req;
> > +		xrow_decode_dml((struct xrow_header *)row, &req, 0);
> 
> xrow_decode_dml() may fail, you should handle it.
> 
Agree, fixed.
> > +		/* Never confirm LSN out of order. */
> > +		panic("LSN for %u is used twice or COMMIT order is broken: "
> > +		      "confirmed: %lld, new: %lld, req: %s",
> > +		      (unsigned) row->replica_id,
> > +		      (long long) vclock->lsn[row->replica_id],
> > +		      (long long) row->lsn,
> > +		      request_str(&req));
> > +	}
> > +	return vclock_follow(vclock, row->replica_id, row->lsn);
> > +}
> > +
> >  #if defined(__cplusplus)
> >  } /* extern "C" */
> >  
> > diff --git a/test/xlog/log_request_broken_lsn_panic.test.lua b/test/xlog/log_request_broken_lsn_panic.test.lua
> 
> The test doesn't pass when run twice in a row:
> 
>   yes xlog/log_request_broken_lsn_panic.test.lua | head -n 10 | xargs ./test-run.py -j 1 --long
> 
> Please fix.

I corrected the test. My understanding is that the issue stemmed
from the fact that I used the xlog/replica.lua script without specifying
repl_master parameter and on the second test run, the environment already
contained the MASTER variable set from the previous run, so it caused a
failed replication attempt.

In order to fix this, I replaced the replica.lua script with panic.lua
since the latter doesn't expect replication config.

> 
> Also, the test name is rather cumbersome IMHO. What about
> xlog/panic_on_broken_lsn.test.lua ?
> 
OK.

> > new file mode 100644
> > index 0000000..e0b3295
> > --- /dev/null
> > +++ b/test/xlog/log_request_broken_lsn_panic.test.lua
> > @@ -0,0 +1,78 @@
> > +-- Issue 3105: Test logging of request with broken lsn before panicking
> > +-- Two cases are covered: Recovery and Initial Join
> > +env = require('test_run')
> > +test_run = env.new()
> > +
> > +fio = require('fio')
> > +test_run:cmd("setopt delimiter ';'")
> > +function grep_file_tail(filepath, bytes, pattern)
> > +    local fh = fio.open(filepath, {'O_RDONLY'})
> > +    local size = fh:seek(0, 'SEEK_END')
> > +    if size < bytes then
> > +        bytes = size
> > +    end
> > +    fh:seek(-bytes, 'SEEK_END')
> > +    local line = fh:read(bytes)
> > +    fh:close()
> > +    return string.match(line, pattern)
> > +end;
> > +test_run:cmd("setopt delimiter ''");
> > +
> > +-- Testing case of panic on recovery
> > +test_run:cmd('create server replica with script="xlog/panic_replica.lua"')
> > +test_run:cmd('start server replica')
> > +test_run:switch('replica')
> > +
> > +box.space._schema:replace{"t0", "v0"}
> > +lsn = box.info.vclock[1]
> > +box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", lsn + 1)
> > +box.space._schema:replace{"t0", "v1"}
> > +box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", -1)
> > +
> > +test_run:switch('default')
> > +test_run:cmd('stop server replica')
> > +
> > +dirname = fio.pathjoin(fio.cwd(), "panic_replica")
> > +xlogs = fio.glob(dirname .. "/*.xlog")
> > +fio.unlink(xlogs[#xlogs])
> > +
> > +test_run:cmd('start server replica with crash_expected=True')
> > +
> > +logpath = fio.pathjoin(fio.cwd(), 'panic_replica.log')
> > +
> > +-- Check that log contains the mention of broken LSN and the request printout
> > +grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {.*}")
> > +
> > +test_run:cmd('cleanup server replica')
> > +test_run:cmd('delete server replica')
> > +
> > +-- Testing case of panic on initial join
> 
> In tarantool the process of joining a new replica consists of two
> phases: initial join, when the last checkpoint is sent, and final join,
> when xlogs are sent. So this is final join, actually. Let's use phrase
> 'joining a new replica' in comments to avoid confusion.
> 
OK.

> > +test_run:cmd('create server leader with script="xlog/replica.lua"')
> 
> Why do you need a separate master? Why can't you simply bootstrap a
> replica from the default instance? Then you wouldn't need to add the
> new script, xlog/panic_replica.lua. I surmise this is because you need
> to access box.info.replication below while on the default server the
> replica doesn't necessarily have id 2. If this is the reason, then you
> might want to look at test_run.cleanup_cluster().
> 

In the fixed patch, I removed the extra script xlog/panic_replica.lua.
I also added the default server restart to the beginning and the very
end of the test. I expect this will guarantee that replica will always 
have the id 2.

> > +test_run:cmd("start server leader")
> > +test_run:switch('leader')
> > +
> > +box.schema.user.grant('guest', 'super')
> 
> box.schema.user.grant('guest', 'replication')
> 
> > +_ = box.schema.space.create('test')
> > +_ = box.space.test:create_index('pk')
> > +
> > +box.space.test:auto_increment{'v0'}
> > +lsn = box.info.vclock[1]
> > +box.error.injection.set("ERRINJ_RELAY_BREAK_LSN", lsn + 1)
> > +box.space.test:auto_increment{'v1'}
> > +
> > +test_run:cmd('create server replica with rpl_master=leader, script="xlog/panic_replica.lua"')
> > +test_run:cmd('start server replica with crash_expected=True')
> > +fiber = require('fiber')
> > +while box.info.replication == nil do fiber.sleep(0.001) end
> > +while box.info.replication[2].downstream.status ~= "stopped" do fiber.sleep(0.001) end
> > +
> > +test_run:switch('default')
> > +-- Check that log contains the mention of broken LSN and the request printout
> > +grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 6, new: 6, req: {.*}")
> > +
> > +test_run:cmd('stop server leader')
> > +test_run:cmd('cleanup server leader')
> > +test_run:cmd('delete server leader')
> > +
> > +test_run:cmd('cleanup server replica')
> > +test_run:cmd('delete server replica')

Please find the fixed patch below.
============================================================================

From 8299d697f0dff8d552c84d1450f70cf5fbde7e55 Mon Sep 17 00:00:00 2001
From: Sergei Kalashnikov <ztarvos@gmail.com>
Date: Tue, 28 Aug 2018 18:05:34 +0300
Subject: [PATCH v2] xlog: add request details to panic message for broken LSN

Aid the debugging of replication issues related to out-of-order
requests. Adds the details of request/tuple to the diagnostic
message whenever possible.

Closes #3105
---
https://github.com/tarantool/tarantool/issues/3105
https://github.com/tarantool/tarantool/commits/ztarvos/gh-3105-log-request-broken-lsn

Changes in v2:
 - Removed vclock_follow_unsafe()
 - Renamed the new function vclock_follow_xrow(),
   removed extra params and moved it to the header.
 - Added error injections and simplified the test.
 - Added test for replica join case.
 - Removed trailing spaces.


 src/box/applier.cc                     |   6 +-
 src/box/recovery.cc                    |   4 +-
 src/box/relay.cc                       |   6 ++
 src/box/vclock.c                       |   8 +-
 src/box/vclock.h                       |   8 ++
 src/box/wal.c                          |  13 ++-
 src/box/xrow.h                         |  31 ++++++
 src/errinj.h                           |   2 +
 test/box/errinj.result                 |   4 +
 test/xlog/panic_on_broken_lsn.result   | 168 +++++++++++++++++++++++++++++++++
 test/xlog/panic_on_broken_lsn.test.lua |  72 ++++++++++++++
 test/xlog/suite.ini                    |   2 +-
 12 files changed, 305 insertions(+), 19 deletions(-)
 create mode 100644 test/xlog/panic_on_broken_lsn.result
 create mode 100644 test/xlog/panic_on_broken_lsn.test.lua

diff --git a/src/box/applier.cc b/src/box/applier.cc
index dbb4d05..5d87867 100644
--- a/src/box/applier.cc
+++ b/src/box/applier.cc
@@ -336,8 +336,7 @@ applier_join(struct applier *applier)
 		coio_read_xrow(coio, ibuf, &row);
 		applier->last_row_time = ev_monotonic_now(loop());
 		if (iproto_type_is_dml(row.type)) {
-			vclock_follow(&replicaset.vclock, row.replica_id,
-				      row.lsn);
+			vclock_follow_xrow(&replicaset.vclock, &row);
 			xstream_write_xc(applier->subscribe_stream, &row);
 		} else if (row.type == IPROTO_OK) {
 			/*
@@ -503,8 +502,7 @@ applier_subscribe(struct applier *applier)
 			 * the row is skipped when the replication
 			 * is resumed.
 			 */
-			vclock_follow(&replicaset.vclock, row.replica_id,
-				      row.lsn);
+			vclock_follow_xrow(&replicaset.vclock, &row);
 			struct replica *replica = replica_by_id(row.replica_id);
 			struct latch *latch = (replica ? &replica->order_latch :
 					       &replicaset.applier.order_latch);
diff --git a/src/box/recovery.cc b/src/box/recovery.cc
index fe14def..77357f0 100644
--- a/src/box/recovery.cc
+++ b/src/box/recovery.cc
@@ -135,7 +135,7 @@ recovery_scan(struct recovery *r, struct vclock *end_vclock)
 		return;
 	struct xrow_header row;
 	while (xlog_cursor_next(&cursor, &row, true) == 0)
-		vclock_follow(end_vclock, row.replica_id, row.lsn);
+		vclock_follow_xrow(end_vclock, &row);
 	xlog_cursor_close(&cursor, false);
 }
 
@@ -266,7 +266,7 @@ recover_xlog(struct recovery *r, struct xstream *stream,
 		 * in case of forced recovery, when we skip the
 		 * failed row anyway.
 		 */
-		vclock_follow(&r->vclock,  row.replica_id, row.lsn);
+		vclock_follow_xrow(&r->vclock, &row);
 		if (xstream_write(stream, &row) == 0) {
 			++row_count;
 			if (row_count % 100000 == 0)
diff --git a/src/box/relay.cc b/src/box/relay.cc
index 138e66d..9f07655 100644
--- a/src/box/relay.cc
+++ b/src/box/relay.cc
@@ -676,6 +676,12 @@ relay_send_row(struct xstream *stream, struct xrow_header *packet)
 	if (packet->replica_id != relay->replica->id ||
 	    packet->lsn <= vclock_get(&relay->local_vclock_at_subscribe,
 				      packet->replica_id)) {
+		struct errinj *inj = errinj(ERRINJ_RELAY_BREAK_LSN,
+					    ERRINJ_INT);
+		if (inj != NULL && packet->lsn == inj->iparam) {
+			packet->lsn = inj->iparam - 1;
+			say_warn("injected broken lsn: %lld", packet->lsn);
+		}
 		relay_send(relay, packet);
 	}
 }
diff --git a/src/box/vclock.c b/src/box/vclock.c
index 2189ea8..b5eb280 100644
--- a/src/box/vclock.c
+++ b/src/box/vclock.c
@@ -42,13 +42,7 @@ vclock_follow(struct vclock *vclock, uint32_t replica_id, int64_t lsn)
 	assert(lsn >= 0);
 	assert(replica_id < VCLOCK_MAX);
 	int64_t prev_lsn = vclock->lsn[replica_id];
-	if (lsn <= prev_lsn) {
-		/* Never confirm LSN out of order. */
-		panic("LSN for %u is used twice or COMMIT order is broken: "
-		      "confirmed: %lld, new: %lld",
-		      (unsigned) replica_id,
-		      (long long) prev_lsn, (long long) lsn);
-	}
+	assert(lsn > prev_lsn);
 	/* Easier add each time than check. */
 	vclock->map |= 1 << replica_id;
 	vclock->lsn[replica_id] = lsn;
diff --git a/src/box/vclock.h b/src/box/vclock.h
index 928717c..111e291 100644
--- a/src/box/vclock.h
+++ b/src/box/vclock.h
@@ -199,6 +199,14 @@ vclock_sum(const struct vclock *vclock)
 	return vclock->signature;
 }
 
+/**
+ * Update vclock with the next LSN value for given replica id.
+ *
+ * @param vclock Vector clock.
+ * @param replica_id Replica identifier.
+ * @param lsn Next lsn.
+ * @return previous lsn value.
+ */
 int64_t
 vclock_follow(struct vclock *vclock, uint32_t replica_id, int64_t lsn);
 
diff --git a/src/box/wal.c b/src/box/wal.c
index cd068a4..ade2c71 100644
--- a/src/box/wal.c
+++ b/src/box/wal.c
@@ -186,6 +186,11 @@ xlog_write_entry(struct xlog *l, struct journal_entry *entry)
 	struct xrow_header **row = entry->rows;
 	for (; row < entry->rows + entry->n_rows; row++) {
 		(*row)->tm = ev_now(loop());
+		struct errinj *inj = errinj(ERRINJ_XLOG_BREAK_LSN, ERRINJ_INT);
+		if (inj != NULL && inj->iparam == (*row)->lsn) {
+			(*row)->lsn = inj->iparam - 1;
+			say_warn("injected broken lsn: %lld", (*row)->lsn);
+		}
 		if (xlog_write_row(l, *row) < 0) {
 			/*
 			 * Rollback all un-written rows
@@ -652,8 +657,7 @@ wal_assign_lsn(struct wal_writer *writer, struct xrow_header **row,
 			(*row)->lsn = vclock_inc(&writer->vclock, instance_id);
 			(*row)->replica_id = instance_id;
 		} else {
-			vclock_follow(&writer->vclock, (*row)->replica_id,
-				      (*row)->lsn);
+			vclock_follow_xrow(&writer->vclock, *row);
 		}
 	}
 }
@@ -878,9 +882,8 @@ wal_write(struct journal *journal, struct journal_entry *entry)
 				 */
 				if (vclock_get(&replicaset.vclock,
 					       instance_id) < (*last)->lsn) {
-					vclock_follow(&replicaset.vclock,
-						      instance_id,
-						      (*last)->lsn);
+					vclock_follow_xrow(&replicaset.vclock,
+							   *last);
 				}
 				break;
 			}
diff --git a/src/box/xrow.h b/src/box/xrow.h
index 4721670..3fc007a 100644
--- a/src/box/xrow.h
+++ b/src/box/xrow.h
@@ -522,6 +522,37 @@ xrow_to_iovec(const struct xrow_header *row, struct iovec *out);
 void
 xrow_decode_error(struct xrow_header *row);
 
+/**
+ * Update vclock with the next LSN value for given replica id.
+ * The function will cause panic if the next LSN happens to be
+ * out of order. The details of provided row are included into
+ * diagnostic message.
+ *
+ * @param vclock Vector clock.
+ * @param row Data row.
+ * @return Previous LSN value.
+ */
+static inline int64_t
+vclock_follow_xrow(struct vclock* vclock, const struct xrow_header *row)
+{
+	assert(row);
+	assert(row->replica_id < VCLOCK_MAX);
+	if (row->lsn <= vclock->lsn[row->replica_id]) {
+		struct request req;
+		const char *req_str = "n/a";
+		if (xrow_decode_dml((struct xrow_header *)row, &req, 0) == 0)
+			req_str = request_str(&req);
+		/* Never confirm LSN out of order. */
+		panic("LSN for %u is used twice or COMMIT order is broken: "
+		      "confirmed: %lld, new: %lld, req: %s",
+		      (unsigned) row->replica_id,
+		      (long long) vclock->lsn[row->replica_id],
+		      (long long) row->lsn,
+		      req_str);
+	}
+	return vclock_follow(vclock, row->replica_id, row->lsn);
+}
+
 #if defined(__cplusplus)
 } /* extern "C" */
 
diff --git a/src/errinj.h b/src/errinj.h
index 64d13b0..c658cd7 100644
--- a/src/errinj.h
+++ b/src/errinj.h
@@ -118,6 +118,8 @@ struct errinj {
 	_(ERRINJ_VY_LOG_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
 	_(ERRINJ_VY_RUN_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
 	_(ERRINJ_VY_INDEX_FILE_RENAME, ERRINJ_BOOL, {.bparam = false}) \
+	_(ERRINJ_RELAY_BREAK_LSN, ERRINJ_INT, {.iparam = -1}) \
+	_(ERRINJ_XLOG_BREAK_LSN, ERRINJ_INT, {.iparam = -1}) \
 
 ENUM0(errinj_id, ERRINJ_LIST);
 extern struct errinj errinjs[];
diff --git a/test/box/errinj.result b/test/box/errinj.result
index c7e4ce2..dca2c2d 100644
--- a/test/box/errinj.result
+++ b/test/box/errinj.result
@@ -16,6 +16,8 @@ errinj.info()
     state: 0
   ERRINJ_WAL_WRITE:
     state: false
+  ERRINJ_XLOG_BREAK_LSN:
+    state: -1
   ERRINJ_HTTPC_EXECUTE:
     state: false
   ERRINJ_VYRUN_DATA_READ:
@@ -60,6 +62,8 @@ errinj.info()
     state: false
   ERRINJ_WAL_WRITE_DISK:
     state: false
+  ERRINJ_RELAY_BREAK_LSN:
+    state: -1
   ERRINJ_VY_LOG_FILE_RENAME:
     state: false
   ERRINJ_VY_RUN_WRITE:
diff --git a/test/xlog/panic_on_broken_lsn.result b/test/xlog/panic_on_broken_lsn.result
new file mode 100644
index 0000000..b14514b
--- /dev/null
+++ b/test/xlog/panic_on_broken_lsn.result
@@ -0,0 +1,168 @@
+-- Issue 3105: Test logging of request with broken lsn before panicking
+-- Two cases are covered: Recovery and Joining a new replica
+env = require('test_run')
+---
+...
+test_run = env.new()
+---
+...
+test_run:cmd('restart server default with cleanup=True')
+fio = require('fio')
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function grep_file_tail(filepath, bytes, pattern)
+    local fh = fio.open(filepath, {'O_RDONLY'})
+    local size = fh:seek(0, 'SEEK_END')
+    if size < bytes then
+        bytes = size
+    end
+    fh:seek(-bytes, 'SEEK_END')
+    local line = fh:read(bytes)
+    fh:close()
+    return string.match(line, pattern)
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+-- Testing case of panic on recovery
+test_run:cmd('create server panic with script="xlog/panic.lua"')
+---
+- true
+...
+test_run:cmd('start server panic')
+---
+- true
+...
+test_run:switch('panic')
+---
+- true
+...
+box.space._schema:replace{"t0", "v0"}
+---
+- ['t0', 'v0']
+...
+lsn = box.info.vclock[1]
+---
+...
+box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", lsn + 1)
+---
+- ok
+...
+box.space._schema:replace{"t0", "v1"}
+---
+- ['t0', 'v1']
+...
+box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", -1)
+---
+- ok
+...
+test_run:switch('default')
+---
+- true
+...
+test_run:cmd('stop server panic')
+---
+- true
+...
+dirname = fio.pathjoin(fio.cwd(), "panic")
+---
+...
+xlogs = fio.glob(dirname .. "/*.xlog")
+---
+...
+fio.unlink(xlogs[#xlogs])
+---
+- true
+...
+test_run:cmd('start server panic with crash_expected=True')
+---
+- false
+...
+logpath = fio.pathjoin(fio.cwd(), 'panic.log')
+---
+...
+-- Check that log contains the mention of broken LSN and the request printout
+grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {.*}")
+---
+- 'LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {type:
+  ''REPLACE'', lsn: 1, space_id: 272, index_id: 0, tuple: ["t0", "v1"]}'
+...
+test_run:cmd('cleanup server panic')
+---
+- true
+...
+test_run:cmd('delete server panic')
+---
+- true
+...
+-- Testing case of panic on joining a new replica
+box.schema.user.grant('guest', 'super')
+---
+...
+_ = box.schema.space.create('test')
+---
+...
+_ = box.space.test:create_index('pk')
+---
+...
+box.space.test:auto_increment{'v0'}
+---
+- [1, 'v0']
+...
+lsn = box.info.vclock[1]
+---
+...
+box.error.injection.set("ERRINJ_RELAY_BREAK_LSN", lsn + 1)
+---
+- ok
+...
+box.space.test:auto_increment{'v1'}
+---
+- [2, 'v1']
+...
+test_run:cmd('create server replica with rpl_master=default, script="xlog/replica.lua"')
+---
+- true
+...
+test_run:cmd('start server replica with crash_expected=True')
+---
+- false
+...
+fiber = require('fiber')
+---
+...
+while box.info.replication == nil do fiber.sleep(0.001) end
+---
+...
+while box.info.replication[2].downstream.status ~= "stopped" do fiber.sleep(0.001) end
+---
+...
+test_run:switch('default')
+---
+- true
+...
+logpath = fio.pathjoin(fio.cwd(), 'replica.log')
+---
+...
+-- Check that log contains the mention of broken LSN and the request printout
+grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 5, new: 5, req: {.*}")
+---
+- 'LSN for 1 is used twice or COMMIT order is broken: confirmed: 5, new: 5, req: {type:
+  ''INSERT'', lsn: 5, space_id: 512, index_id: 0, tuple: [2, "v1"]}'
+...
+test_run:cmd('cleanup server replica')
+---
+- true
+...
+test_run:cmd('delete server replica')
+---
+- true
+...
+test_run:cmd('restart server default with cleanup=True')
diff --git a/test/xlog/panic_on_broken_lsn.test.lua b/test/xlog/panic_on_broken_lsn.test.lua
new file mode 100644
index 0000000..d4abf6f
--- /dev/null
+++ b/test/xlog/panic_on_broken_lsn.test.lua
@@ -0,0 +1,72 @@
+-- Issue 3105: Test logging of request with broken lsn before panicking
+-- Two cases are covered: Recovery and Joining a new replica
+env = require('test_run')
+test_run = env.new()
+test_run:cmd('restart server default with cleanup=True')
+
+fio = require('fio')
+test_run:cmd("setopt delimiter ';'")
+function grep_file_tail(filepath, bytes, pattern)
+    local fh = fio.open(filepath, {'O_RDONLY'})
+    local size = fh:seek(0, 'SEEK_END')
+    if size < bytes then
+        bytes = size
+    end
+    fh:seek(-bytes, 'SEEK_END')
+    local line = fh:read(bytes)
+    fh:close()
+    return string.match(line, pattern)
+end;
+test_run:cmd("setopt delimiter ''");
+
+-- Testing case of panic on recovery
+test_run:cmd('create server panic with script="xlog/panic.lua"')
+test_run:cmd('start server panic')
+test_run:switch('panic')
+
+box.space._schema:replace{"t0", "v0"}
+lsn = box.info.vclock[1]
+box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", lsn + 1)
+box.space._schema:replace{"t0", "v1"}
+box.error.injection.set("ERRINJ_XLOG_BREAK_LSN", -1)
+
+test_run:switch('default')
+test_run:cmd('stop server panic')
+
+dirname = fio.pathjoin(fio.cwd(), "panic")
+xlogs = fio.glob(dirname .. "/*.xlog")
+fio.unlink(xlogs[#xlogs])
+
+test_run:cmd('start server panic with crash_expected=True')
+
+logpath = fio.pathjoin(fio.cwd(), 'panic.log')
+
+-- Check that log contains the mention of broken LSN and the request printout
+grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 1, new: 1, req: {.*}")
+
+test_run:cmd('cleanup server panic')
+test_run:cmd('delete server panic')
+
+-- Testing case of panic on joining a new replica
+box.schema.user.grant('guest', 'super')
+_ = box.schema.space.create('test')
+_ = box.space.test:create_index('pk')
+box.space.test:auto_increment{'v0'}
+lsn = box.info.vclock[1]
+box.error.injection.set("ERRINJ_RELAY_BREAK_LSN", lsn + 1)
+box.space.test:auto_increment{'v1'}
+
+test_run:cmd('create server replica with rpl_master=default, script="xlog/replica.lua"')
+test_run:cmd('start server replica with crash_expected=True')
+fiber = require('fiber')
+while box.info.replication == nil do fiber.sleep(0.001) end
+while box.info.replication[2].downstream.status ~= "stopped" do fiber.sleep(0.001) end
+
+test_run:switch('default')
+logpath = fio.pathjoin(fio.cwd(), 'replica.log')
+-- Check that log contains the mention of broken LSN and the request printout
+grep_file_tail(logpath, 256, "LSN for 1 is used twice or COMMIT order is broken: confirmed: 5, new: 5, req: {.*}")
+
+test_run:cmd('cleanup server replica')
+test_run:cmd('delete server replica')
+test_run:cmd('restart server default with cleanup=True')
diff --git a/test/xlog/suite.ini b/test/xlog/suite.ini
index 8ee9720..ffc812e 100644
--- a/test/xlog/suite.ini
+++ b/test/xlog/suite.ini
@@ -4,7 +4,7 @@ description = tarantool write ahead log tests
 script = xlog.lua
 disabled = snap_io_rate.test.lua
 valgrind_disabled =
-release_disabled = errinj.test.lua panic_on_lsn_gap.test.lua
+release_disabled = errinj.test.lua panic_on_lsn_gap.test.lua panic_on_broken_lsn.test.lua
 config = suite.cfg
 use_unix_sockets = True
 long_run = snap_io_rate.test.lua
-- 
1.8.3.1